Injury sidelines Arsenal's Mertesacker

Arsenal's German centre back Per Mertesacker will be sidelined for a few months with a knee problem, the Premier League club's manager Arsene Wenger told a news conference on Tuesday.

He was injured in Friday's friendly away to Lens and ruled out of the pre-season tour of the United States which kicks off on Friday against the MLS All-Stars in San Jose, California.

Mertesacker's injury means Wenger may have to rush back Laurent Koscielny, who is resting after helping France reach the Euro 2016 final, for the start of the Premier League season.

Gabriel has also missed the US tour with tonsillitis, leaving Calum Chambers as their most experienced centre back.

England Under-21 central defender Rob Holding, 20, joined the club from Bolton Wanderers last week.

Arsenal start their league campaign at home to Liverpool on August 14.