Arsenal will be without Santi Cazorla for three months after scans revealed he has suffered ligament damage in his knee.
Cazorla, who is 31 next week, sustained the injury during their 1-1 draw against Norwich. However, the Spaniard was forced to continue after Arsenal had used all their subs.
The news comes just a week after Francis Coquelin was ruled out for a similar time period through injury and serves a real blow to their title aspirations.
With fitness doubts also over Mikel Arteta and Mathieu Flamini, Wenger will surely now have to be active in the January transfer market to ensure their title hopes do not fade.
Cazorla has made at least 247 more passes than any other player in the Premier League this season (1,037).
For more stats on Santi Cazorla, click here to visit his WhoScored player page