Carlton was just seconds away from confirming a finals spot before a Melbourne goal condemned the Blues to defeat, while Fremantle downed West Coast by 24 points in the Western Derby.
Earlier, Geelong claimed the AFL minor premiership with a dominant 60-point win over Gold Coast.
The Western Bulldogs kept their season alive with a narrow win over GWS and Adelaide overcame North Melbourne by 29 points.
Melbourne breaks Carlton hearts, taking lead with 15 seconds remaining in MCG thriller
Kysaiah Pickett's snap shot under pressure in the dying seconds has given Melbourne a thrilling five-point win over Carlton in a huge boost to the reigning premiers' chances of locking in an AFL top-four spot.
It looked as though the undermanned Blues would pull off a major upset when Charlie Curnow kicked his only goal of the night to put them eight points in front deep into time-on of the final quarter.
But the Demons hit back through dangerous forward Jake Melksham. Then Pickett floated his last-gasp effort through from the top of the goal square with just 15 seconds left on the clock.
It sealed Melbourne's 11.13 (79) to 10.14 (74) victory at the MCG on Saturday night, which maintained their top-four position ahead of a crunch clash with Brisbane in round 23.
Carlton's bid to end a nine-year finals drought is still in their own hands heading into the blockbuster against arch-rivals Collingwood.
No more than two goals split Melbourne and Carlton in a finals-like arm wrestle that Demons coach Simon Goodwin feels can set his side up for another shot at September glory.
"It was an important night for us to win a close game of footy, we haven't done that all year really, and to show enormous character as a group," Goodwin said.
"It's the type of win that this group can embody and continue to move forward.
"They're important because you can draw on these experiences as you go forward and we've needed to be on the better end of one of these experiences.
"It was a great game of footy and either team could've won, but in the end this is the type of grit and character that you need to show."
Angus Brayshaw (38 disposals, 12 clearances) and Clayton Oliver (29, six) starred in the midfield for Melbourne despite both copping close attention from Will Setterfield.
Melksham finished with four goals and Pickett two, while Harry McKay and Jack Martin kicked three majors each for the Blues.
Carlton captain Patrick Cripps was cleared to play after a marathon tribunal and appeals process and was jeered by Demons supporters every time he went near the contest.
But the tough ball-winner sent those fans hoarse with 26 disposals and 10 clearances as the leader of an injury-hit Blues midfield.
Adam Cerra (adductor strain) was a late withdrawal, joining George Hewett (back) and Matthew Kennedy (jaw) on the sidelines, but Cripps, Sam Walsh (27 disposals) and Sam Docherty (28) took the fight to the Demons' vaunted engine room.
Both sides equalled their lowest first-half scores of the season in a dour opening but goals flowed more freely in the second half.
The lead changed hands four times in the last quarter as Martin twice put Carlton ahead but Melksham and Pickett had the final say in the tense battle.
"The last couple of minutes we didn't quite get right, so I guess it's easy to sort of focus on that last two minutes," Blues coach Michael Voss said.
"It leaves you gutted, it leaves you disappointed, but I'm also really proud at the same time.
"I thought our players were really brave right through the whole night, but it hurts."
Dockers defeat Eagles in fiery Derby
Fremantle secured a home final after overcoming a bad case of the goalkicking wobbles to post a 24-point win over West Coast in a spiteful Western Derby.
All-in melees and individual tit-for-tats were common throughout the rain-affected match in Perth but Fremantle booted 4.11 to 2.3 after half-time to secure the 9.17 (71) to 7.5 (47) win in front of 53,816 spectators.
The result means the Dockers cannot finish lower than sixth, and they can still secure a prized top-four berth if they beat GWS next week and other results fall their way.
Dockers ruckman Sean Darcy won the Glendinning-Allan Medal as best afield for his 16-disposal, 57 hit-out effort.
Blake Acres (29 disposals, one goal), Will Brodie (28 disposals, seven clearances), and David Mundy (25 disposals, eight clearances) dominated in the midfield courtesy of Darcy's dominance.
But despite snaring the win, doubts still remain about Fremantle's ability to thrive in the wet.
The Dockers entered the match having lost to Gold Coast, Collingwood and Melbourne in slippery conditions this year and they were unable to put West Coast to the sword despite the Eagles missing 10 first-choice players.
Fremantle's wayward goal kicking ensured West Coast remained within striking distance for most of the match.
But it was the defensive duo of Tom Barrass and Shannon Hurn that truly epitomised West Coast's fighting spirit.
Barrass (20 disposals, 12 marks) restricted Rory Lobb to just 0.1 from seven disposals, while Hurn racked up 28 touches and nine rebound 50s.
Lobb was subbed out late in the match after aggravating his right shoulder injury in the third quarter.
The match was a willing contest befitting a Derby with a huge melee breaking out in the opening quarter in what will no doubt result in a flurry of fines.
Caleb Serong was target number one early on, with Jack Redden doing his best to ruffle the feathers of the Fremantle star.
The tactic worked a treat, with Serong the core culprit when Fremantle gave away a 50-metre penalty that led to a goal on the line to Redden.
Redden gave away a 50-metre penalty of his own late in the opening term to gift a goal to Andrew Brayshaw.
Jackson Nelson targeted Brayshaw at every opportunity, with the Brownlow Medal fancy visibly frustrated at times.
An early downpour ensured the first half was played in slippery conditions and the Dockers led by four points at the long break.
The Dockers dominated the third term but their return of 2.8 meant the 17-point margin was still within reach for West Coast.
However, with Darcy dominating the ruck, the Eagles could not work their way back into the match despite fighting right until the end.
Geelong thrash Gold Coast, claim minor premiership
Relentless Geelong have effectively secured the AFL's minor premiership with a 60-point thrashing of Gold Coast at Carrara.
The Cats moved eight points clear at the top of the ladder via their 12th-straight win, defeating the Suns 18.11 (119) to 9.5 (59) on Saturday.
The win may have come at a cost however with Rhys Stanley subbed out in the third quarter with an issue to his upper left leg.
Only Collingwood, who play Sydney on Sunday, can join the Cats on 17 wins but the Magpies are too far behind on percentage to realistically be any chance of toppling Chris Scott's team from top spot.
And, if the Cats beat struggling West Coast at Kardinia Park next weekend, it won't matter what the Magpies do in their final two games.
With a favourite son of both clubs in Gary Ablett watching on after the dual Brownlow Medallist was awarded Suns' life membership before the game, Geelong were simply too good for the hosts.
Tyson Stengle booted three goals to take his tally past 40 goals for the year while Jeremy Cameron also kicked three majors to move within two of Carlton's Ed Curnow in the Coleman Medal race.
Cameron's tally could have been more as he kicked three behinds as well as his goals as he finished the game with 10 score involvements.
Cameron Guthrie was impressive for the Cats with 30 disposals and four clearances, while Patrick Dangerfield returned from a calf niggle with 24 touches, seven clearances and nine score involvements.
Izak Rankine, sporting a new peroxide hairdo, showed speculation over his future amid a contract offer from Adelaide isn't affecting his on-field performance with two goals for the Suns.
The small forward's night ended on a sour note however after he came off in the final quarter with a left shoulder injury following a tackle by Cats' superstar Dangerfield.
The Suns also lost foundation player Sam Day to a left knee injury in the third term.
Suns co-captain Touk Miller finished with a game-high 36 disposals, while Brandon Ellis picked up 32 touches.
Stengle's smart finish from a Tom Hawkins tap led to the opening goal of the game before Dangerfield surged from the centre clearance and set up Cameron's first.
Gold Coast gave away three goals with turnovers as they struggled to get out of their defensive 50, and Geelong racked up seven goals to be 31 points clear at the first change.
A further five majors in the second term continued the carnage, with Geelong extending their advantage by 20 at the main break.
The Suns came out firing with a three-goal burst at the start of the third quarter but the Cats rallied with three of their own to hold a 55-point lead at the final turn.
Cameron spent the last 12 minutes on the bench as Geelong eased to their 17th win of the season.
Dogs still alive thanks to tight win over Giants
The Western Bulldogs have survived an almighty scare from rivals GWS to prevail by five points and keep their AFL finals hopes alive.
Trailing until young gun Jamarra Ugle-Hagan slotted his first goal of Saturday's game with 10 minutes remaining, the Bulldogs outlasted the injury-hit Giants 9.8 (62) to 8.9 (57).
The fatigued Giants, who sit 16th on the ladder and are enduring a horror season, continued to press hard and had opportunities to reclaim the lead in the dying stages at Docklands Stadium.
But a strong contested mark from Bulldogs defender Bailey Dale with 40 seconds remaining proved to be enough as Luke Beveridge's team clung onto a crucial 11th win of the season.
The Bulldogs (11-10) have to defeat Hawthorn in Launceston next Saturday in their final regular season game and rely on Carlton and Richmond inside the top-eight faltering to be any chance of playing finals for a fourth straight year.
The Giants came in with a slow, kick-and-chip game plan, frustrating the Bulldogs by playing keepings off in a low-scoring scrap with a combined tally of just six goals kicked in the first-half.
However, the match opened up in the third term as both teams traded blows.
After falling 10 points behind, the Bulldogs surged back ahead with four goals in 10 minutes as defender Bailey Williams delivered an unexpected cameo with two of those majors.
Ruckman Tim English set the standard, asserting his dominance in the centre square to give the Bulldogs first use of the football.
GWS tall Lachlan Keeffe slotted a miracle goal from the pocket late in the third quarter as the Giants pinched the lead back by the final change.
However, Keefe (groin) was unable to finish the match and was subbed out for Xavier O'Halloran early in the final term.
Bulldogs defender Zaine Cordy will face a nervous wait ahead of the match review officer's finding after bumping Tanner Bruhn off the ball, dazing the Giants youngster as he staggered to the bench.
The incident led to Bruhn's teammates remonstrating with Cordy, sparking scenes that have become trademark in games between GWS and the Bulldogs.
Interim coach Mark McVeigh will likely lead the Giants for the final time next Saturday as they head to Canberra to host finals-bound Fremantle.
Crows outlast depleted North for third straight win
Adelaide have denied inspirational midfielder Ben Cunnington a fairytale AFL return as they overcame a spirited North Melbourne challenge to run away to a 29-point victory on Saturday.
The Crows proved too slick for the Kangaroos and finished stronger, kicking the only five goals of the final term on their way to a 15.13 (103) to 10.14 (74) triumph at Adelaide Oval.
The gripping contest was a clash of styles as the Crows were more damaging when moving the ball on the outside while the Kangaroos had a stranglehold around the stoppages for much of the match.
Adelaide's Darcy Fogarty continued his impressive form and looked a threat throughout booting four goals while Taylor Walker finished with three.
Jordan Dawson was also influential as he gathered 33 disposals and had 834m gained, while Rory Laird worked his way into the match after a slow start to finish with 25 touches.
The Crows (8-13) have now won three matches in a row and pushed past their seven wins in 2021.
Cunnington impressed in his first AFL match for 385 days after overcoming two bouts of cancer but it was emerging star Luke Davies-Uniacke that looked most likely to propel the Kangaroos to a rousing victory.
Davies-Uniacke was outstanding as he gathered game-highs for 37 disposals, 11 clearances and 10 inside 50s, and kicked a goal as his partnership with Jy Simpkin (30 touches, 10 clearances) continued to blossom.
Spiritual leader Cunnington battled well throughout the match and finished with 17 disposals, six of them in his preferred contested manner.
The Kangaroos (2-19) were dominant at the centre bounces, especially early, but the visitors failed to make the Crows pay as they kicked 5.6 to 3.0 for the term to take an eight-point lead into the main break. It left room for the momentum to swing and the teams headed into the final quarter with scores level.
While North had it all to play for in Cunnington's return, with captain Jack Ziebell subbed out of the match and Jaidyn Stephenson also sidelined, it was Adelaide who finished with the running.
The Crows will be desperate to stretch their winning streak into their final-round Showdown against Port Adelaide next Saturday night, while the Kangaroos need a win over Gold Coast to avoid their worst win-loss record since 1972.
Ladder
AAP
