Arsenal returned to third place in the Premier League table with a 1-0 win at 10-man Fulham yesterday, while Reading and Queens Park Rangers slipped ever closer to relegation.
Arsenal, who started with England midfielder Jack Wilshere on the bench, were given a huge advantage in the 12th minute at Craven Cottage when Steve Sidwell was shown a straight red card for catching Mikel Arteta on the ankle with his studs.
Sidwell had only just returned from a three-match ban following a red card at home to QPR.
The breakthrough arrived from an unfamiliar source two minutes before half-time.
Theo Walcott's free-kick was headed across goal by Laurent Koscielny and the Frenchman's centre-back partner Per Mertesacker arrived unmarked to head the ball home from close range.
It should have been a straightforward win, but the visitors were unable to kill the game and then lost Giroud to a late red card after he fouled Stanislav Manolev.
Victory lifted Arsenal above Chelsea, but both the Stamford Bridge club and fifth-place Tottenham Hotspur now have two games in hand on Arsene Wenger's side.
Chelsea will regain third place if they win at Liverpool today, while Spurs can close to within two points of their north London rivals if they overcome second-place Manchester City.
At the other end of the table, QPR and Reading appear to be living on borrowed time after both sides lost and saw three of the sides above them win.
Bottom club Reading went down 2-1 at Norwich City, to leave Nigel Adkins' men 10 points from safety with only 12 points to play for.
QPR are above Reading on goal difference alone after a 2-0 loss at home to Stoke City, who claimed a first win in eight games to ease their own relegation fears.
The defeats for the bottom two mean that both sides could be relegated as early as tomorrow, but only if fourth-bottom Aston Villa win at leaders Manchester United.
"It looks in tatters doesn't it, it's very difficult," said QPR manager Harry Redknapp. "We've got to try to win a game or two, we've got to go to Reading next week and try to win. It looks almost impossible doesn't it. It would take a real miracle."
Paolo Di Canio enjoyed a second successive win as Sunderland manager as his new club overcame Everton 1-0 to pull six points clear of the drop zone, while Wigan lost 2-0 to West Ham.
Meanwhile, Newcastle United slipped three places to 16th with a 1-1 draw at West Brom, and Swansea City and Southampton drew 0-0.