Arsenal striker Robin van Persie has sustained a "partial fracture" to his foot.
The Dutch player suffered the injury when scoring the equalising goal in the 2-1 Premiership defeat of Manchester United, and now faces up to six weeks on the sidelines.
After watching captain Thierry Henry score a stoppage-time winner, Gunners boss Arsene Wenger revealed he had hoped to let substitute van Persie - currently the club's top scorer - rest until United's opener forced his hand.
The 23-year-old had been struggling with an ankle injury in the build-up to the game.
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