Donegal's Patrick McBrearty will miss the rest of the season with a knee injury.
The Kilcar forward was taken of early in the second half of Sunday's Ulster Senior Football Championship final against Fermanagh.
Leaving Clones on Sunday, McBrearty had ice strapped to the front of his knee and was using a crutch for a period.
Donegal emphatically booked their place in the Super 8s as they swept aside the Ernemen to lift the Anglo-Celt Cup.
McBrearty took a heavy knock shortly before half-time at Clones while scoring a point. He re-emerged for the second period but was replaced within minutes.
It has now been confirmed that he has ruptured his anterior cruciate ligament.
His absence is a huge blow to Donegal, whose opening Super 8 fixture will be against Dublin at Croke Park in July.
The 24-year-old was the county's top point-scorer in this year's league campaign and registered an impressive 19 points in Donegal's four-game provincial campaign.
The Tir Chonaill men romped to their first provincial title since 2014, averaging an impressive 2-19 a game.
Under new manager Declan Bonner, Donegal have drawn plaudits for their attacking style of play which has brought the best out of star forwards McBrearty and Michael Murphy.