Derry defender Kevin Johnston will miss the rest of the season after suffering a knee injury during the Ulster SFC semi-final defeat by Donegal.
The Dungiven player sustained a heavy knock late in the 1-9 to 0-10 loss to Donegal at Clones on Saturday.
A scan has revealed serious damage which has ruling him out for club and county for the rest of this year.
"It's disappointing, it looks like Kevin will be out for a long spell," said Derry manager Brian McIver.
McIver is disappointed referee Rory Hickey allowed play to continue on Saturday night while Johnston was lying on the ground.
"The lad was lying injured and the match was going on around him.
"If a player has a serious injury, then the medical staff have to be allowed to attend to him.
"The game was stopped several times for other injuries, yet Kevin's was the most serious of the lot and the play went on.
"That should not have happened."
Johnston has been a regular for Derry since making his debut in February 2014 and McIver admitted he will be a huge loss for the remainder of their season.
"Kevin had been playing great, and it's really disappointing for him on a personal level.
"As a squad, we just have to get our heads right now for the qualifiers."
Derry will play Wexford, conquerors of Down last weekend, in a Round 2B qualifier on Saturday 11 July.