London Irish survived a stint with just 12 men to condemn Gallagher Premiership leaders Saracens to their first league defeat of the campaign.
The absorbing contest, which Irish won 29-20, was marred by two red cards and particularly concerning scenes as Saracens hooker Tom Woolstencroft received lengthy treatment after appearing to be knocked out.
Newly-appointed England coach Steve Borthwick was watching on as Saracens suffered their first defeat in 10 league matches as a poor start and ill-discipline cost them dear at the Gtech Community Stadium.
Both teams had a player sent off in the first half and each side ended up scoring two tries, with Paddy Jackson's five penalties proving the difference as the struggling Irish recorded a third league win of the season.
London Irish captain Adam Coleman was first to be dismissed in the 16th minute as he thundered into the head of Saracens hooker Woolstencroft, who appeared to be knocked out before receiving lengthy treatment and being carried off on a stretcher. Ugo Monye, on punditry duties for BT Sport, said of the red card: "This is probably the most blatant one we've seen this season."
Saracens flanker Ben Earl was shown the first red card of his career 15 minutes later for a high tackle on Tom Pearson.
Ollie Hassell-Collins and Chandler Cunningham-South scored tries for Irish with Jackson converting both.
Kapeli Pifeleti and Sean Maitland touched down for Saracens, with Owen Farrell kicking two penalties and two conversions.
Irish began strongly to secure a line-out platform in the opposition 22. From there, they secured possession to test Saracens' defence to the full before Benhard van Rensburg's pass gave Hassell-Collins the chance to brush past Farrell's tackle to score.
Jackson converted but his side suffered an injury blow when centre Will Joseph hobbled from the field.
The hosts then received two setbacks in quick succession. First Farrell's penalty put Saracens on the scoreboard to reward a period of sustained pressure before Coleman was sent off, leaving the home side seemingly with a mountain to climb.
However they still picked up the next points when Jackson kicked two penalties in quick succession as decisions by referee Matt Carley were continually questioned by Farrell. The Saracens skipper also queried the red card shown to Earl in the 31st minute, with Jackson again on target with the resulting penalty.
But an out-of-sorts Saracens remained in contention when replacement hooker Pifeleti forced his way over. Farrell converted, but with the last kick of the half, Jackson slotted over his fourth penalty, this time from the half-way line, to give Irish a 19-10 interval lead.
Five minutes after the restart, Saracens scored their second try. A speculative chip through from Elliot Daly bounced awkwardly for Irish wing Lucio Cinti, with Maitland on hand to pick up the pieces.
The visitors looked set to take control but Jackson succeeded with his fifth penalty to temporarily keep them at bay, before Rory Jennings was fortunate to escape with just a yellow card for a high challenge on Billy Vunipola with 20 minutes remaining.
Worse was to follow for Irish when they went down to 12 players, with Rob Simmons sin-binned for collapsing a maul, but remarkably a ragged Saracens could not score in their absence.
On their return, Farrell kicked a penalty but Irish secured a thrilling victory when Cunningham-South finished off a flowing move to send Irish's biggest crowd of the season home happy.
Saracens boss Mark McCall later described his side as "rattled and distracted" as they lost their unbeaten record in this season's Gallagher Premiership. After securing nine consecutive victories, the runaway Premiership leaders needed just one more to secure their best ever run.
Director of rugby McCall had few complaints about the result, admitting Irish fully deserved the win, but he was far from impressed with his side's performance.
He said: "Hats off to Irish as they were by far the better team. We never played with any energy and were well off the pace. Our decision-making was poor and we allowed ourselves to be rattled and distracted.
"When they went down to 12, you have to find a way to score but we didn't as our skill levels weren't accurate enough. Irish have been unfortunate to lose in a number of great games this season and their league position is false. I'd like to have a look again at Ben's dismissal as it felt like it was very low and their player's momentum was going to the floor."
Despite a run of poor results, London Irish director of rugby Declan Kidney never doubted his side's ability to come good.
He said: "We didn't get too despondent as I knew we weren't far away. In adversity it's very easy to start doubting yourselves but I never did with this group.
"It was some game to watch with lots of ebbs and flows and the match was won on tight margins. We are learning how to win, and tonight will help us a lot with that but one swallow doesn't make a summer. Our boys had a bit to prove tonight whereas Sarries were coming off two good wins in Europe so that may have helped us a bit."
Read more:
Rob Howley and double Grand Slam winner both in frame to join Warren Gatland's Wales coaching team
New rugby laws announced for 2023 as host of changes coming
Wales international gutted by huge talent's exit amid 'nightmare mess'
Lion calls for 'scumbag' to be sacked and coach blown away by Welsh rugby's 'best player'
