Southampton sealed a late victory against Arsenal thanks to an 85th minute Charlie Austin goal.
Braces from Danny Ings and Henrikh Mkhitaryan seemed to secure each side a point but a last-gasp winner saw the Saints steal the victory.
The result ended Arsenal's 22 games unbeaten spell as the Gunners now sit five points behind Tottenham Hotspur.
Saints secure half-time lead
Arsenal began the game on the front foot with the lions share of possession and it was the away side who threatened first.
Pierre-Emerick Aubameyang latched onto a superb chipped pass from Mattéo Guendouzi but was unable to beat Alex McCarthy in the Saints goal.
However, from then on the Saints began to work their way into the game.
Nathan Redmond came close and just minutes later Danny Ings opened the scoring - a superb goal it was too.
Matt Targett worked his way down the left flank before whipping in an inch-perfect cross which Ings headered home.
The goal had their new boss, Ralph Hasenhuttl jumping for joy on the touchline.
The Saints had come alive and the Gunners were struggling to get out of their own half.
However, completely against the run of play Henrikh Mkhitaryan levelled the proceedings.
Similarly to the opening goal from the home side, Nacho Monreal worked his way down the left side before executing a fine cross in which the Armenian midfielder directed home with his head.
Just minutes after the equalising goal, Jan Bednarek was forced to pull off a goal-saving intervention to prevent Aubameyang a certain tap in.
The game from then on till the last few minutes of the half became a midfield scrap.
But with just two minutes to go in the half, Ings headered home his second of the afternoon.
All three goals have almost been carbon copies of each other. This time Redmond found himself out wide on the right before producing a superb cross for Ings to head home.
The looping header from the 26-year-old left Bernd Leno stranded and the German international was only able to watch as the ball found the back of the net.
Saints prevail
In typical Unai Emery fashion, Alexander Lacazette was brought on at half-time for Hector Bellerin.
Straight from the off, Aubameyang was fed in by Mkhitaryan but was unable to poke the ball under the Saints goalkeeper.
It was becoming a serious case of deja vu as Mkhitaryan scored his second of the game to level the score again.
Oriol Romeu was caught napping in the middle of the park as Lacazette stole the ball from him and played in Mkhitaryan whose deflected shot wrong-footed McCarthy.
The deflection came as a huge slice of luck for the visitors despite starting the second 45 the brighter of the two sides.
Considering the blistering start to the second period from the Gunners after their tempo steadied after the goal.
However, the Saints' goalkeeper was let off the hook after taking far too long to clear his lines he was intercepted by Aubameyang 25-yards from his goal.
He will have his defender, Bednarek to thank after the Polish defender put in a goal-saving challenge.
With just 15 minutes left on the clock, Leno pulled off one of the saves of the season to keep his side level.
From a corner, Maya Yoshida's header cannoned goalwards but a strong right-hand from the Arsenal goalkeeper was enough to deny the Saints defender.
Shane Long scored from the rebound but his celebrations were cut short with the effort being ruled offside.
Less than five minutes remained of the game when Shane Long's cross found Austin at the far post as the Englishman sealed the victory for the Saints.
Austin nodded home the fourth headered goal of the afternoon to give Southampton the lead for the third time of the afternoon.