The 25-year-old was indispensable for Everton last season, featuring in all 38 of their Premier League games, playing 3414 minutes, more than any other outfield player.
Garner could now miss their Premier League opener against Crystal Palace at the Hill Dickinson Stadium on August 22nd.
Everton have released a statement confirmed that Garner has undergone surgery to address a groin injury.
“James Garner has undergone successful surgery to address a groin issue identified during pre-season,” it reads.
“The Blues midfielder has begun his rehabilitation at Finch Farm and is progressing as expected, with a return to first-team training being targeted around the opening week of the Premier League season, subject to his continued recovery.”
