Swansea City defender Alfie Mawson has had knee surgery.
The 24-year-old centre-back was one of the few Swansea players to enhance their reputation despite their relegation from the Premier League.
Mawson earned a first call-up to the England senior squad for the friendlies with Netherlands and Italy in March, but has still to win his first cap.
The Swans say his hopes of playing in the World Cup "are over" but expect him to return during pre-season.
Mawson was an ever-present for Swansea's 2017-18 league campaign despite his knee problem, which stems from the injury sustained in the warm-up before their FA Cup game at Sheffield Wednesday last February.
He joined Swansea for £5m from Barnsley in August 2016 on a four-year deal.
Despite that long-term contract at the Liberty Stadium, Swansea may struggle to hold onto their star defender once fit with admiring Premier League clubs likely to pursue Mawson.