Arsenal have been dealt a blow ahead of the Premier League season after Jack Wilshere was ruled out for several weeks with a hairline crack to his left fibula.
The midfielder, who missed last week's Community Shield victory over Chelsea, suffered the injury during an accidental collision in training.
Arsenal manager Arsene Wenger told the club's official website: "I had a bad surprise because it is a hairline crack in his fibula that makes him a few weeks out.
"There is minimal damage apart from the bone damage - there is no damage at all apart from that.
"It was a collision in training and it was all completely accidental."
The news represents yet another blow for the England international, who has been plagued with injuries, particularly to his ankles, throughout his career.
The 23-year-old was absent for five months of the 2014-15 season after suffering ankle ligament damage in a fixture against Manchester United in November.
He returned to play a part in Arsenal's run-in and helped the team defend the FA Cup in a 4-0 rout of Aston Villa in May.
Arsenal start the season against West Ham at the Emirates Stadium on Sunday and Wenger confirmed Alexis Sanchez - recently back in training following the Copa America - is likely to miss out, together with Danny Welbeck.
"Alexis is back in training but I don't think he will be involved on Sunday, it is a bit early maybe," said Wenger.
"We have to decide that at the end of the week, but I don't think he will be involved.
"[Welbeck] is not too far away, but he is not ready for Sunday."
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