Goalkeeper Petr Cech will be sidelined for up to a month with a hamstring injury, Arsenal have announced.

Cech was replaced early in the second half of Saturday’s Premier League match against Watford, with Bernd Leno coming on to keep a clean sheet as the Gunners won 2-0.

Arsenal said in an injury update on their official website ahead of the Europa League tie away to Qarabag in Baku on Thursday that Cech had a “left hamstring injury” and was “expected to return to full training in three to four weeks”.