Neil Gallagher admitted that Donegal were "relieved" to have beaten Derry after an Ulster SFC semi-final he said was "in the balance the whole way through".
Marty O'Reilly's 45th-minute goal proved the difference as Rory Gallagher's side advanced to their fifth successive Ulster final.
Gallagher, at the heart of a lot of Donegal's positive play, said there was a lot of room for improvement.
"A lot of sloppy passes went astray," Gallagher said of Donegal's performance. "And a couple of bad shots.
"We'd a lot of wides and stuff like that. In the end, the goal was a big difference, I suppose."
Gallagher said Donegal had failed to make good decisions in the face of a stifling Saturday evening and Derry's determination.
"It was a close evening, and Derry put us under intense pressure," he said.
"It was an intense game, and when you're under that kind of pressure, you have to try and rely on making good decisions, but that doesn't always happen like that, you know.
"We're just relieved to get through by two points, because it was in the balance the whole way through."
Having built up a useful 0-4 to 0-1 lead after 11 minutes, Donegal endured a 20-minute score freeze and Derry were pleased to be on level terms at the break..
Derry came within three points of Donegal is last year's Ulster quarter-final, undone by a Donegal surge right after half-time, and this time they suffered the same fate.
Michael Murphy, by his standards, had a relatively subdued game but still kicked two inspiring points in the second half. The first came before the game's only goal, ten minutes into the second half, when a break by Neil Gallagher created the overlap for Martin O'Reilly who rounded Thomas Mallon and finished well. Five points between the teams looked like serious daylight but Derry would not lie down.
From there Derry had the better of it which will give Donegal cause for reflection ahead of their bid to win a fourth Ulster title in five years.
Another scoring drought ensued - this time timed at 18 minutes. Derry responded with three points from Lynch, O'Boyle and Barry Heron, a second half sub, to close to gap to two points with play almost at the hour mark.
Murphy landed a huge point seven minutes from time but Derry came again, their wing back Ciaran McFaul scoring a point a minute later.
The rest of the match was played out scoreless but there was the threat of Derry breaking through for a match-winning goal. They never did and they never really went close but Donegal will know that a major improvement is needed in the days ahead.
ulster sfc semi-final: donegal 1-9 derry 0-10
Donegal's Mark McHugh gets past Danny Heavron of Derry during the Ulster SFC semi-final in Clones. Pic: Sportsfile