Jack Wilshere has undergone surgery on an ankle injury, West Ham have confirmed.
The midfielder missed West Ham's 3-1 win at Everton on Sunday as Manuel Pellegrini's side ended a run of four straight losses in the Premier League.
West Ham announced on Monday the England international has had an operation, but while the club's head of medical Richard Collinge did not provide a timetable for the midfielder's return, he indicated Wilshere is not expected to be out for too long.
"Jack underwent successful surgery in London on Monday morning for a minor ongoing ankle issue," Collinge told West Ham's website.
"The surgeon was happy with the procedure and all went as planned.
"We envisage he will only need a relatively short period of rest and will then start his rehabilitation.
"Jack is focused and determined to get back training and playing as soon as possible."
Wilshere has started four Premier League games since signing a three-year deal following his departure from Arsenal.
The midfielder had gone the distance in the first three contests, but exited in the 64th minute in the fourth, a 1-0 loss to Wolves, before missing out on the first fixture following the international break.
West Ham host Chelsea in a London derby on Sunday with a home game against Manchester United also on their schedule before the end of September.