Southampton have missed the chance to overtake Manchester United in the Premier League table.
A Jonjo Shelvey wonder-strike late in the game gave Swansea a 1-0 win at St Mary's this afternoon.
The Saints' bad day was compounded when Ryan Bertrand received a straight red card late on for a poor challenge on Modou Barrow.
Arsenal are up to fifth this evening - four second-half goals saw the Gunners beat Aston Villa 5-0 at the Emirates.
Olivier Giroud, Mesut Ozil, Theo Walcott, Santi Cazorla and Hector Bellerin all managed goals.
After this weekend's action, Chelsea remain at the top with a five-point gap separating them from second-placed Manchester City. Manchester United are five point behind their city rivals, and a point ahead of both Southampton and Arsenal.
Final scores
Arsenal 5 - 0 Aston Villa
(A: Giroud 8', Ozil 56', Walcott 63', Cazorla 75' pen, Bellerin 90 +1')
Southampton 0 - 1 Swansea
(Swansea: Shelvey 83')