Arsenal midfielder Jack Wilshere has suffered a hairline fracture to his right ankle and could be out for six to eight weeks.
The 23-year-old was injured by a heavy tackle in training on Saturday, a day before Sunday's 1-0 win over Chelsea in the Community Shield.
He will not require surgery on the small bone crack, but is expected to miss up to two months of the season.
Wilshere missed five months of last season after injuring his left ankle.
He required two operations after suffering ligament damage in November and returned for the Gunners' final six games of the campaign, including the FA Cup final success against Aston Villa.
In June he played in England's friendly draw with the Republic of Ireland and their victory over Slovenia in a European Championship qualifier.
Wilshere's career has been plagued with injury problems, particularly in his ankles.
Both ankles have required surgery since he first sustained a stress fracture in his right ankle during pre-season in 2011 and was ruled out for 15 months.
In May, Arsenal boss Arsene Wenger said Wilshere needed "one or two years without problems" to get his "full confidence and belief back".
Wilshere's ankle injury history
- October 2009: Five weeks
- July 2011: 15 months
- March 2013: Six weeks
- May 2013: Seven weeks
- October 2013: Two weeks
- January 2014: Two weeks
- March 2014: Two months
- October 2014: Two weeks
- November 2014: Five months
- August 2015: Expected up to eight weeks