Andy Murray wound back the clock on Rod Laver Arena, pulling off a major upset over Italian 13th seed Matteo Berrettini.
And Novak Djokovic returned to Melbourne Park a winner, even with his hamstring heavily strapped.
While Australian wildcard Kimberly Birrell recorded another upset to stun Estonia's Kaia Kanepi.
Key events
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Live updates
Djokovic returns a dominant winner
By Paul Johnson
Novak Djokovic walked onto Rod Laver Arena to cheers and fans singing his nickname, he walked off it, once again a dominant winner.
The Serbian star, who was absent last year after a COVID vaccine-related immigration battle with the Morrison government resulted in him being deported, showed he is back in a big way.
Fans who stuck around late into the night and early Wednesday morning to see their hero waved Serbian flags and sang "Nole, Nole, Nole" throughout as Djokovic flexed every muscle including his heavily strapped left hamstring in a stunning straight sets victory over Spanish world number 75 Roberto Carballes Baena.
The 6-3, 6-4, 6-0 scoreline in favour of the nine-times champion belied how close the match mostly was.
It was Carballes Baena who had the first big chance in the opening set, but with Djokovic down 0-40 at 2-all, the Spaniard could do little as Djokovic reeled off five straight points before telling the umpire he was leaving for the bathroom.
That was considered a no-no as the Serb did not have permission but he got back before time was called and continued on his way, breaking Carballes Baena that very game on a run of 11 straight points.
Those handful of games were absurd tennis from Djokovic before Carballes Baena and he took the opening set before Carballes Baena found his best tennis in the second set.
The Spaniard took it to Djokovic, who looked proppy on the left leg after chasing a drop shot early in the second set but he brushed it off as the two traded heavy and long groundstroke rallies.
The willingness to do so seemed to indicate the hamstring Djokovic injured in Adelaide might be ok after all.
And when Djokovic broke Carballes Baena in the seventh game of the second set it broke the Spaniard's resolve.
Djokovic took the second set and then raced through the third with confidence to round out a resounding return to Melbourne Park, which saw him thank the crowd for their support afterwards.
"Thank you for giving me such a welcoming and reception I could only dream of," Djokovic said.
"I am happy to be back in Australia where I had the biggest success in my career.
"This court is the most special court in my life."
Djokovic takes the second
By Paul Johnson
It's been valiant resistance from Carballas Baena thus far but Rod Laver Arena belongs to Djokovic and he is just starting to flex his muscles.
The Spaniard had been going with Djokovic for the most part of this set but when he was broken in the 7th game it broke him just a little bit.
He staved off Djokovic pressure to hold for 4-5 but Djokovic confidently served out the set to lead 6-3, 6-4.
Djokovic up a set but just looked a bit proppy
By Paul Johnson
Novak Djokovic is up a set but the injury concerns have been raised slightly again.
Chasing a drop shot at 2-all in the second set the former world number one got there before losing the point to Carballes Baena.
He then immediately hopped a couple of times on his strapped left leg and spent the back end of his game speaking to his team.
Carballes Baena leads the second set 3-2 on serve, Djokovic took the first 6-3.
Players leave outside courts as rain comes down
By Paul Johnson
In an issue that has been going all night the rain is back and this time players are not sticking around.
No immediate word on whether play will resume tonight but it's not great news for a slew of Aussies, who are all at crucial points in their matches.
Here's where play stands right now in matches that have been stopped:
- Kokkinakis (AUS) leads Fognini 6-1, 6-2, 4-2
- Vukic (AUS) trails Holt 4-6, 6-1, 2-4
- Purcell (AUS) trails Ruusuvori 6-4, 3-6, 4-6, 6-6
Djokovic takes opening set
By Paul Johnson
Brilliant and occasionally bizarre things happen when Novak Djokovic is on the tennis court.
His toilet break was random as the umpire called time before he got back but he remained unfazed and ratcheted up the tempo against Roberto Carballes Baena.
From there the remainder of the set was pretty comfortable for Djokovic as he took it 6-3 with an emphatic ace down the middle.
Issue with the umpire aside it was all pretty impressive.
Djokovic saves triple break point
By Paul Johnson
That may be the best chance Roberto Carballes Baena will get in this one.
The Spaniard just had 0-40 on the Djokovic serve and butchered it.
5 points later and Djokovic has a 3-2 lead before telling the umpire in a matter of fact manner that he is going to the toilet.
That seemed to be a case of the Serbian star should not have been allowed to go but he just decided to anyway.
Kokkinakis up 2 sets
By Paul Johnson
It nay have taken a while to start but blink and right now you would miss this one.
Thanasi Kokkinakis is just one set away from a second round match-up with Andy Murray.
The Australian emphatic against Fabio Fognini and up 6-1, 6-2.
It's the Djoker show right now but this was special from Andy Murray
By Paul Johnson
Aussie O'Connell goes down
By Paul Johnson
Chris O'Connell's Australian Open is over.
After taking the opening set from American Jenson Brooksby, the rising US star found his range and knocked of the Aussie 3-6, 6-2, 6-3, 6-2.
Was a tough draw for the Australian ad Brooksby will now likely face second seed Casper Ruud.
Heavily strapped Djokovic cheered onto RLA
By Paul Johnson
Novak Djokovic has been serenaded with cheers and chants of 'Nole, Nole, Nole' as he walked onto Rod Laver Arena for his first real match at this venue since 2021.
And while that will warm the hearts of his legions of fans who waved flags as he strolled onto Melbourne Park's main court, Djokovic did so with his left hamstring heavily taped.
The hamstring injury, which he suffered against Daniil Medvedev in Adelaide, which he eventually won saw him cancel one practice session during the week and has been the subject of some conjecture.
In an exhibition last week he wore kinesio tape on the hamstring against Nick Kyrgios.
Kokkinakis is flying
By Paul Johnson
The Australian has taken the opening set against Fabio Fognini 6-1 in little over half an hour.
He's also just broken the Italian in the opening game of the 2nd set.
This one might be over fast.
'Frustrated' Jabeur picks up level and win
By Paul Johnson
That was a bizarre match.
For two sets Ons Jabeur was struggling with her game and Tamara Zidansek was pushing her every step of the way.
Then the third set, where Zidansek came off her level, Jabeur upped hers and the 2nd seed advanced 7-6 (10/8), 4-6, 6-1.
Was almost like she said 'not today' rolled Zidansek and got out of dodge.
The final set lasted just 28 minutes of a match that went over 2 hours.
"I wasn't playing very well and she was putting a lot of pressure on me.
"She doesn't give up and brings every ball in, so I was pretty frustrated.
"I just told myself to be number two in the world and just win this match."
Kokkinakis takes the early break
By Paul Johnson
The Aussie has the early ascendancy on a pretty loud KIA Arena.
He leads Fognini 4-1 and looks to be in control right now.
Kokkinakis getting back underway
By Paul Johnson
The rain has stopped for now and the Kokkinakis v Fognini battle is back on, on KIA Arena.
Can the Aussie get past the Italian veteran to book a match against Andy Murray?
Stay with us to find out. 1-0 Kokkinakis
Women's second seed in trouble
By Paul Johnson
This one isn't going to plan for Ons Jabeur.
The women's second seed was given a tough draw against 2021 French Open semifinalist Tamara Zidansek and now she's into a third set.
Jabeur isn't playing well either with plenty of unforced errors coming from her racket.
If she doesn't amend that she too could be another high-profile casualty on day 2.
Adelaide champ Bencic dominant again
By Paul Johnson
Belinda Bencic might just be a player to watch for the women's singles title.
The Swiss star dominated Daria Kasatkina in the Adelaide 2 women's singles final and she's just picked up where she left off at Melbourne Park.
The 12th seed destroyed Bulgaria's Viktoriya Tomova 6-1, 6-2 in just over an hour.
Bencic may have never won a grand slam title but she is the reigning Olympic champion and has form at other majors so a seep run here is possible.
Rain continues to play havoc
By Paul Johnson
The weather is at it again.
Just as Thanasi Kokkinakis and Fabio Fognini looked to get their round one clash underway on KIA Arena, the rain came down again.
The same happened to Aleksander Vukic. Not sure what the tournament organisers will do from here but will keep you posted.
De Minaur delivers impressive victory
By Paul Johnson
Australia's Alex De Minaur may not get the attention compatriots Nick Kyrgios and Thanasi Kokkinakis sometimes do but he has delivered an emphatic round one victory.
The 22nd-seeded Australian took little time in destroying Taiwan's Yu-Hsiou Hsu 6-2, 6-2, 6-3.
De Minaur, who managed to knock off Rafael Nadal earlier this summer was undeniable on John Cain Arena.
His improved power off the ground was again on show in the performance as he booked a battle with either big-serving American John Isner or wily Frenchman Adrian Mannarino.
De Minaur in cruise mode
By Paul Johnson
This is looking academic now for Alex De Minaur.
The 22nd seed is up 6-2, 6-2 in his opening round match and his wheels aren't too bad either.
Have a look at this get.
'Great champion': Vanquished Berrettini lauds Murray
By Paul Johnson
Matteo Berretini said Andy Murray handled the indoor conditions for their match better but when it came down to it he fluffed his lines when it mattered.
"I had a match point. I missed on his ball. That's sums up of the match," Berrettini said in a matter of fact media appearance.
He then went on to pay tribute to Murray for still being able to play at such a high level after multiple surgeries.
"He loves to play these kind of matches, Berrettini said.
"He's a great champion. I said it so many times. Personally it was great to play with that atmosphere against him.
"It's impressive what he could do after so many surgeries, after all the kilometres that he ran in his career.
"It's impressive. It just shows how much he loves the game."
Murray will play either another Italian in Fabio Fognini or Australia's Thanasi Kokkinakis in the second round.
