Mikel Arteta’s side struck twice from corners and also conceded from the same route in a match that underlined the increasing importance of set-pieces in the Premier League.
William Saliba’s first goal since December 2024 put Arsenal ahead in the first half at the Emirates Stadium.
Piero Hincapie’s own goal drew Chelsea level from one of Reece James’ deadly corners just before the break.
But Timber won a priceless three points for Arsenal with his second-half header before Chelsea winger Pedro Neto was sent off for a second booking.
The Gunners’ second successive league win reestablished their five-point lead over second-placed Manchester City, who have a game in hand and had closed the gap with a 1-0 victory at Leeds on Saturday.
After enduring scathing criticism of their mentality during a recent wobble that breathed new life into the title race, Arsenal have got back on track just in time as they followed last weekend’s 4-1 rout of Tottenham with a far more tense triumph.
