Michael Murphy inspired Donegal to a second half blitzing of Derry to progress to an Ulster semi-final for the fourth successive year under Jim McGuinness.
Questions had been asked of Donegal in the build-up to this quarter-final tie at Celtic Park and the jury was still out after a poor first half display.
The visitors trailed by 0-6 to 0-4 at the interval, but effectively won the game with a quick-fire 1-3 in seven electric minutes after the restart, inspired by captain Michael Murphy.
Donegal actually scored 1-5 without reply early in the second half to completely turn the game around.
“It was a tough game. We tried to create a situation were we could maximise the fellas on the bench coming into the game,” said Donegal boss, Jim McGuinness.
“We were happy enough with the first half to be honest with you.
“We created a couple of goal chances playing against the breeze and we knew Derry were going to bring a possession game to the match.
“We knew that they would keep a lot of ball and try and keep moving the ball. They were trying to be patient and we had to be patient.
“We felt with a bit of a breeze in our backs in the second half, we could get some quality ball in to Michael and get runners off him as well and we got the goal out of that.
“Derry brought a massive challenge to Donegal and we knew that was going to be the case.
“You could see out there on the pitch that they were very confident, well coached and looking forward to the game and they were going to bring a lot of challenges to us.
“As the game went on we were happy that were able to deal with them and we managed to get a grip on the game which was positive from our own point of view.”
Derry boss Brian McIver was left to rue a poor start to the second half.
“We’re disappointed. We played really, really well in the first half but we had a horrible 10 minutes after half-time when Donegal played well and won every breaking ball,” added McIver, who managed Donegal to the Football League title in 2007.
“They worked the goal and the couple of scores and that was the difference at the end of the day.
“We should have been more ahead at half-time but listen it was that 10 minutes which cost us.”