Arsenal midfielder Mathieu Flamini has been ruled out of his side's Premier League clash against Liverpool on Saturday.
The Frenchman, who has been in terrific form for the Gunners since rejoining the club on a free transfer in the summer, had to be substituted after just eight minutes against Crystal Palace last weekend.
Arsenal boss Arsene Wenger has revealed his groin injury is not as bad as first feared - but believes the former AC Milan midfielder will also miss his side's Champions League encounter against Borussia Dortmund.
Wenger, speaking to reporters, said: “Flamini is a short-term injury and he could be available for Manchester United. He’s out for tomorrow and he’s out for Dortmund.
“We have just Arteta back. [Serge] Gnabry will not be available and all the other long-term injuries are not back; no [Alex Oxlade-]Chamberlain, no [Lukas] Podolski and no [Abou] Diaby.
“For Theo, the earliest [will be] Manchester United. I think he will be a bit short for Manchester United.”
Premier League leaders Arsenal go into Saturday's encounter at the Emirates Stadium two points ahead of Liverpool.
Wenger is hopeful his side can bounce back from their 2-0 midweek Capital One Cup defeat against Chelsea.
“The mood is very strong, very United and as well very focused. We know where the priorities are – in the Premier League and the Champions League. Our mood is positive,” he added.
Wenger will be desperate to have a full strength squad at his disposal over the next two months, as the Gunners have to face the likes of Borussia Dortmund, Manchester United, Manchester City and Chelsea before the end of December.