LONDON (REUTERS) - Arsenal climbed back into the Premier League's top four for the first time since December when they won 2-1 at West Bromwich Albion thanks to two goals from Tomas Rosicky despite having defender Per Mertesacker sent off on Saturday.

The victory moved the Gunners to 56 points, one more than Chelsea, who slipped back to fifth, at least until they play Sunderland at Stamford Bridge on Sunday.

Rosicky, whose season has been disrupted by injury, headed Arsenal ahead after 20 minutes and scored the second from a rebound in the 50th minute.

Mertesacker was sent off for a foul in the penalty area on Shane Long after 71 minutes and James Morrison scored from the spot to set up a nervous finale for the Gunners.

Aston Villa moved out of the relegation zone and improved their chances of staying up with a 3-1 win at Stoke City.

Norwich City drew 2-2 with Swansea City at Carrow Road.