Arsenal striker Robin van Persie could be out for a month after injuring his knee while playing for Netherlands in Wednesday's Euro 2008 qualifier against Slovenia.
"We will know later today (Thursday) how bad it is but the early signs are he will not be able to perform for us in the next four weeks," manager Arsene Wenger told the club's Web site (www.arsenal.com).
Swiss defender Philippe Senderos also hurt his back on midweek international duty and will be out for two weeks. But William Gallas, Jens Lehmann and Tomas Rosicky are fit and available for the visit of Bolton Wanderers on Saturday.
