The Arsenal ace had to quit Holland's 2-0 victory over Slovenia, and he is set to be submitted to further medical tests.

"It looks like a knee injury," Wenger told Arsenal TV Online. "We will know later today how bad it is but the early signs are that he will not be able to perform for us in the next four weeks.

"It is a big blow. Robin is a striker, a supportive striker and important on set-pieces as well. I hope he will be back soon and we'll do the maximum to get him back."

The 24-year-old international striker has been in a prolific form for the Gunners this season leading them to the top of the English table as he scored five goals in seven matches.