Theo Walcott scored the quickest goal of the Premier League season to secure Arsenal a 1-0 win at Queens Park Rangers to keep his club on course for UEFA Champions League qualification.
QPR, whose relegation had been confirmed by last week's 0-0 draw at Reading, were slowly out of the blocks and conceded the only goal with only 20 seconds on the clock.
Harry Redknapp's side recovered to make a game of it, but were unable to create a clear-cut opening as Arsenal moved back into third position, albeit having played two games more than fourth-placed Chelsea, and one more than Tottenham in fifth.
Arsenal were in front after just 20 seconds when sloppy play from former Gunners full-back Armand Traore was punished when Mikel Arteta slipped in Walcott and his scruffy finish found its way past Rob Green.
Walcott came close to a second goal for the visitors on 26 minutes when he was played in by Tomas Rosicky, but his low shot struck the post.
QPR started to respond and created their best chance on 28 minutes when Andros Townsend cut in from the right, Bobby Zamora helped the ball on, but Park Ji-sung fired over.
Tal Ben Haim, who has scored just one goal in English football, then tried his luck from 30 yards after winning possession on the halfway line, but his shot was comfortably saved by Wojciech Szczesny.
The Arsenal keeper was tested more severely nine minutes into the second half by Townsend's swerving effort before producing a more routine stop from Loic Remy's low attempt.
Arsenal still carried a threat going forwards and Green awkwardly parried Santi Cazorla's dipping shot before saving low at the near post from Walcott.
England winger Walcott was a lively outlet for Arsenal and a 25-yard piledriver from the right side of the pitch was fumbled by Green with 13 minutes to go.
QPR came closest to an equaliser on 83 minutes when Szczesny was forced into a full-length save to turn away Remy's curling shot, but Arsenal held on for a first win at Loftus Road since 1990.
Walcott's winner was his 20th goal of the season and Arsene Wenger praised the winger's growing maturity after the game.
"His finishing is better, in his duels he is stronger and he plays with more belief," said Wenger.
"You get to a stage where you're 24, which he is now, that's when a player becomes really more mature and you've seen that with his goalscoring record."
Meanwhile, QPR boss Harry Redknapp dismissed suggestions that there was a lack of spirit on display from his side in the early stages.
Redknapp said: "I felt to go a goal down within a minute, we showed fantastic spirit. We hung in there and we could have gone under after conceding a goal in a minute.
"After that I felt we were every bit as good as them and could easily have got a result. I thought it was an excellent performance and the spirit was first class.
Sinclair, 24, did not travel with Roberto Mancini's squad to face his former club Swansea after being taken ill during training on Friday.
Sinclair is understood to be in a comfortable condition and his illness is not life-threatening.
The club tweeted a get-well message to the former England Under-21 international, and manager Roberto Mancini said: "Scott had a problem yesterday, I don't think it is a bad situation and it is under control."
