Leaders Arsenal held by Saints
Arsenal's position at the top of the Premier League is under threat after they were held to a 2-2 draw by Southampton at St Mary's Stadium.
Jose Fonte handed Saints a first-half lead against a sluggish Gunners, who had to play the last 10 minutes with only 10 men after Mathieu Flamini saw red.
Arsene Wenger's men came out for the second half with a real sense of purpose and turned the game around thanks to goals from Olivier Giroud and Santi Cazorla in the space of four minutes.
However, Adam Lallana struck to rescue a share of the spoils after 56 minutes.
Flamini was issued a straight red card late on as the north Londoners had to settle for a share of the spoils.
Kicking off 24 hours before their title rivals, Wenger's side were unable to keep up the pressure on Manchester City and Chelsea as they blew what had been an impressive second-half comeback.
They were forced to settle for a point in a hard-fought draw that ended a five-match winning streak, which means they could be usurped at the top of the standings on Wednesday.
Saints began the match impressively, knocking the ball around confidently and dominating possession in an entertaining first half.
Arsenal were lacking fluency and, after bundling wide a Luke Shaw cross after Per Mertesacker failed to clear, debutant Sam Gallagher then stung the palms of Wojciech Szczesny.
Wenger's side were being pegged back in their own half as Saints continued to press and their endeavours were rewarded in the 21st minute.
The ever-impressive Shaw whipped in a cross from the left and Fonte beat Nacho Monreal at the back post, with the centre-back's powerful header too much for Szczesny to claw away.
There were a few hopeful penalty shouts from the Gunners when Fonte's acrobatic clearance went against his own hand, but play continued and Saints came close again at the other end.
Monreal's byline clearance deflected wickedly off Steven Davis and into the six-yard box, where Gallagher met the ball but could only prod wide.
The teenager was proving a nuisance on his full debut and had another chance with half-time approaching, collecting the ball after neat team interplay and only being denied by a last-gasp Laurent Koscielny interception.
The France international almost made another telling impact at the other end before the first half was brought to a close, only for a wonderful Artur Boruc save to deny him from a corner.
They would not be denied for long, though. Three minutes into the second half Arsenal were level as Bacary Sagna met an overhit cross on the right-hand side of the 18-yard box and his low strike went in thanks to a clever touch from Giroud.
The strike was just the beginning of a remarkable start to the second half, with Arsenal turning proceedings on its head in the 52nd minute.
Smelling blood, the north Londoners poured forward and Mesut Ozil's pass was left by Giroud for Cazorla to fire a left-footed strike out of Boruc's reach.
It was a wonderful strike by the Spaniard, although Arsenal's lead lasted less than two minutes.
While many sides could have crumbled, Saints responded impressively.
Rodriguez latched onto a ball down the left flank and pulled back for Lallana, who struck low through Szczesny's legs to pull his side level.
The frantic tempo continued after the leveller as both sides went in hunt of a winner.
Giroud headed away a threatening Morgan Schneiderlin effort, before Ozil broke at pace from his own half and rode an attempted foul to get away a shot that deflected off Fonte and looped over Boruc onto the crossbar.
It was a lucky escape for the hosts, who ended the match on top after Flamini's over-zealous challenge on Schneiderlin was met by a straight red card.
Szczesny did well to deny late Shaw and Fonte efforts in the closing stages, with Arsenal escaping the south coast with a point.