Arsenal defender Thomas Vermaelen will be out for up to three weeks with a calf strain, manager Arsene Wenger said on Saturday.
The Gunners were already missing four defenders when the Belgian international deepened the club's injury woes by limping off during the 1-0 win over London rivals Queens Park Rangers in the Premier League.
"We have lost Vermaelen for two or three weeks so I have to look if I can find somebody on loan," said Wenger.
Vermaelen is normally a central defender but has played as a left back recently to cover for Kieran Gibbs and Andre Santos who have been sidelined with groin and ankle injuries respectively.
"It would be stupid for us to drop points because we don't have a left back," Wenger said after Arsenal climbed to fourth in the table.
"We now have three left backs out. Francis Coquelin came on in this position and did quite well but he is a central midfielder."
Bacary Sagna and Carl Jenkinson, Arsenal's two regular right backs, are also missing through injury.
Meanwhile, Arsenal midfielder Emmanuel Frimpong will join struggling Wolverhampton Wanderers on loan until the end of the season, the London club said on Saturday.
Frimpong sustained a serious knee injury at the start of last season but the 19-year-old has battled back into contention at the Emirates, making 14 appearances for Arsene Wenger's team this campaign.
Fourth-placed Arsenal said Frimpong, who represented England youth but is eligible to play for Ghana at senior level, would join Wolves on January 1.
Wolves are fifth from bottom in the Premier League