Per Mertesacker's first-half header gave Arsenal a 1-0 win at Fulham that moved them up to third place in the Premier League on Saturday, but Arsene Wenger's side struggled to overcome a home side reduced to 10 men for 78 minutes.
The victory moved the Gunners two points clear of Chelsea and five points clear of fifth-placed Tottenham Hotspur, both of whom have two games in hand ahead of their meetings with Liverpool and Manchester City respectively on Sunday.
At this stage of the season, the result is all that matters, but there was enough to concern Wenger, who watched his side labour after Fulham lost Steve Sidwell to a 12th-minute red card following a foul on Mikel Arteta.
Arsenal, who were unconvincing in Tuesday's scoreless home draw with Everton, were also reduced to 10 men themselves when Olivier Giroud was sent off for a similar challenge on Stanislav Manolev in the 90th minute.
Before the game, Fulham manager Martin Jol spoke positively of Arsenal's chances of finishing in the top four and the visitors' hopes were strengthened considerably when Sidwell walked.
The midfielder, who began his career at Arsenal, was making his first-team return after serving a three-match ban following his sending-off against Queens Park Rangers.
Then, Sidwell had a case for complaining he was harshly treated for a challenge on Armand Traore, but on this occasion, the decision was much more clear-cut.
The speed of Arteta's movement was too much for the Fulham man, who lunged in with his studs up, catching the Arsenal player on the ankle. Sidwell will now face a four-match ban, bringing his season to an abrupt end.
Undeterred, Jol's side settled into a pattern of defending deep and attempting to catch Arsenal on the counter-attack, which they did in the 21st minute with a breakaway that should have delivered the opening goal.
Urby Emanuelson surged forward into the visitors' half before releasing Dimitar Berbatov and the forward was denied by a good save from Wojciech Szczesny.
Fulham continued to make headway, particularly down their left flank, where Alex Kacaniklic, recalled last week from a loan spell at Burnley, repeatedly tested Bacary Sagna, the Arsenal right-back.
And had the Swede produced a better final ball, Fulham might have quickly made up for Berbatov's earlier miss.
By contrast, Arsenal's attacking moves lacked penetration and Mark Schwarzer, the Fulham goalkeeper, remained well protected by his back four on his 500th Premier League appearance.
Signs of improvement for the visitors came in the 35th minute when Giroud collected a pass from Santi Cazorla, turned sharply, and drilled a low shot beyond Schwarzer and against the right-hand post.
If Arsenal considered themselves unlucky, they had reason to be grateful when they did take the lead eight minutes later.
Laurent Koscielny completely misjudged an attempted header from Theo Walcott's free-kick, but his miscue diverted the ball across the face of goal, where Mertesacker stooped to head home from close range.
After their impressive first-half efforts, it was a cruel way for Fulham to fall behind, but Jol's side showed no signs of feeling sorry for themselves when the game restarted.
Emanuelson continued to threaten, although the piece of simulation that drew a yellow card for the unfortunate Arteta tarnished his display.
Fulham's consistent pressure was impressive and it was Arsenal who looked jaded throughout the second period, rarely managing to break forward as the home side searched for the equaliser.
They thought it had arrived 12 minutes from time when Manolev followed up a Kieran Richardson free-kick to roll the ball past Szczesny, only for the right-back to be penalised for drifting offside.
Arsenal's nerves were exposed by the hosts' late pressure and they were not helped when Giroud was sent off, but they held on to claim an important win.