Magical Murphy gave Derry defence a torrid time
I thought that the first half yesterday afternoon at Celtic Park mirrored the opening period of the drawn Tyrone and Down game in that both sides set themselves up very defensively.
Derry were a bit like Tyrone in that they didn't drive home their advantage and make better use of possession and they would have been very disappointed to have only gone in at half-time two points up.
Jimmy McGuinness on the other hand would have been delighted to have been so close and then Donegal did what they normally do, up the tempo in the third quarter.
That was the winning of the match as they blitzed Derry with that goal and a number of unanswered points. Michael Murphy going back to the edge of the square was the key moment and he gave the Derry defence a torrid time.
In the first half he was sacrificed as Donegal lined out without their regular midfield and he played in a deeper role but once he got closer to goal, he proved unstoppable.
The half-back line of Ryan McHugh, Karl Lacey and Frank McGlynn were all pivotal to Donegal's success as well.
Lacey did a great marking job on Derry dangerman Mark Lynch while also getting forward to score a point in the first half. McHugh won a lot of breaking ball while McGlynn was vital when pushing forward and played a superb pass for Lee McLoone's goal.
McLoone is one of the unsung heroes of this Donegal side but he played well yesterday.
The introduction of Martin McElhinney was also a huge turning point in the game as he gave them a bit of power and pace around midfield as well as weighing in with an inspirational point.
While Donegal had him and Neil Gallagher to take off the bench and put into midfield, Derry badly missed Fergal Doherty when he had to go off.
He may not be the captain but he's a real leader on the field and they missed his work-rate and physical presence when he departed.
Derry were being talked up after a good league campaign and they will be bitterly disappointed.
The feeling was that this could have been their year in the Ulster Championship but I think that they will regroup and will be tough opposition for any side in the back door.
Donegal on the other hand came in under the radar and to get a win in the Championship at Celtic Park is no mean feat.
It didn't really surprise me as I was talking to Neil McGee before they played Monaghan in the league final and he said not to look at the result of that game as they were only focusing on Derry.
Tyrone got things right in the replay and it was a much better performance. There was more bite in their play and there are plenty of pluses to take from the game, not least the fact that Justy McMahon got 70 minutes under his belt.
Conor Gormley and Stephen O'Neill also made telling contributions from the bench and those two games will stand to Tyrone ahead of Monaghan.
James McCartan will find it difficult to pick his side up as they would have fancied their chances on home soil and while they will hope for a run in the qualifiers it won't be easy for them.