Arsenal lost both Alexis Sanchez and Laurent Koscielny to injury in what could prove to be a damaging 1-1 draw with Norwich City on Sunday.
Mesut Ozil scored his second Premier League goal of the season to put Arsene Wenger's side ahead at Carrow Road but Lewis Grabban equalised from close range just before the break, after Koscielny had been forced off with an apparent hip problem.
Sanchez had to be withdrawn after an hour with a hamstring injury and Norwich came close to a winner when the ball flicked off Gabriel's head and toward his own goal, only for Petr Cech to make a superb save.
Arsenal, who had looked in complete control for the opening half-hour, found themselves on the back foot for much of the rest of the game but Norwich failed to find a second goal that would have given them just a second win in eight league games.
The Gunners, meanwhile, remain fourth on the table after missing a chance to leapfrog Manchester United above them.
Norwich caused a few problems with some early set-pieces and Ozil should have opened the scoring for Arsenal when he was picked out in the box by Nacho Monreal. The German dragged his effort off target, with Sebastian Bassong clearing the danger.
Sanchez drew the first good save out of John Ruddy, forcing the England goalkeeper to parry a fierce shot from inside the box after a fine run from Santi Cazorla.
Ruddy proved his side's undoing with a poor clearance in the 28th minute, allowing Sanchez to slip the ball through to Ozil, who clipped a fine finish into the far corner from the left side of the area.
Alex Neil's team had been comfortably second best but they snatched an equaliser just before the break. Robbie Brady fed the ball into the feet of Grabban, who turned Gabriel superbly before rolling the ball beneath Cech.
And Hoolahan wasted a glorious chance for a second in stoppage time as he side-footed over the crossbar when picked out unmarked at the far post by Andre Wisdom.
Ruddy endured another nervy moment when he completely missed a high bouncing ball from a Sanchez cross early in the second half, but Martin Olsson was on hand to hook clear off the line and away from Ozil.
The game had descended into a more scrappy affair and Arsenal were dealt a further blow when Sanchez was forced off with a hamstring injury after pulling up when running to close down Ryan Bennett in the penalty area.
Hector Bellerin scuffed a shot into the side-netting but the Gunners looked deflated by Sanchez's exit, while Norwich grew in confidence as the home fans sensed an upset.
Cech made a fine low save to prevent an own goal from Gabriel after Olsson's cross and Jonny Howson hooked the ball over the bar from six yards from the resulting corner, before Olivier Giroud headed high 12 yards out from a rare half-chance.
Gabriel made a vital interception to clear Olsson's dangerous cut-back and Joel Campbell just failed to connect with Alex Oxlade-Chamberlain's cross in an end-to-end closing 10 minutes, but neither side could find the winner.
