Arsenal will be without Brazilian midfielder Denilson for two months due to a small fracture in his back.
The talented 21-year-old had started four Premier League matches for The Gunners this season scoring once.
However, he will now spend anywhere up to eight weeks on the sidelines and miss home games against Olympiakos, Blackburn and Birmingham.
"Denilson has a small fracture in his back," confirmed manager Arsenal Wenger. "He will be out for two months."
The Brazilian picked up the injury in the Gunners' 4-2 defeat at Manchester City on 12th September and scans have now revealed the severity of the problem.
The news of Denilson's injury follow hot on the heels of the blow that Nicklas Bendtner will sit out their UEFA Champions League match against the Greeks after being involved in a minor car accident.