Donegal staged a brilliant second-half comeback to beat Mayo despite having Rory Kavanagh sent-off in Ballyshannon.
Kavanagh was shown a straight red card for lashing back at Kevin McLaughlin.
Mayo had made the stronger start and Enda Varley's 10th-minute goal from Conor Mortimer's pass helped them carve out a 1-05 to 0-06 interval advantage.
Donegal made the most of the breeze in the second half and coasted home by seven points with Colm McFadden ending with 0-7 and Michael Murphy 0-5.
Mayo finished the match with 14 men too as Ger Cafferkey was sent-off for two yellow cards.
The win will give Donegal confidence as they travel to play All-Ireland champions Dublin next weekend.
They are now on four points from five matches, level with Laois and just one ahead of bottom-placed Armagh.