Kerry forward Colm 'Gooch' Cooper has suffered a cruciate knee ligament injury, which will rule him out for the entire season.
The 30-year-old was injured during his club Dr Crokes' All-Ireland semi-final defeat to Castlebar on Saturday.
A scan on Monday confirmed the serious injury, which is a huge blow to Kerry's hopes of winning the All-Ireland title.
Cooper won an eighth All Star award last year after a superb display in the All-Ireland semi-final loss to Dublin.
A statement from the Kerry county board confirmed Cooper's injury and added: "he will undergo surgery in due course".
The most high-profile player in gaelic football now faces a major fight to return to the inter-county scene in 2015.