It was the kind of second half that stirs the heart and yet simultaneously almost sends it into overdrive.
The tension was immense, Sunderland, scrapping, fighting, clearing their way to three points of immeasurable importance at the turn of the year.
Forest had all the ball and all the territory, setting nerves on edge. The away support responded to the commitment on show, singing 'things can only get better' with real gusto.
Sunderland were resolute, rarely opened up and largely keeping their opponents to hopeful crosses and long-range efforts.
It was not easy on the eye but it was mightily effective, and the anger in the City Ground as their team floundered said it all.
After a boxing day horror show, Sunderland put back in place the foundations that have seen improvement under Chris Coleman so far, riding their luck in the first half but securing a win built on real spirit and organisation.
That the only goalscorer at half time was McGeady and not former Black Cat Daryl Murphy was remarkable, given that Sunderland had only one shot in the half and Murphy himself had seven.
Sunderland started brightly with Josh Maja showing some good touches and Darron Gibson underlining his recent improvement by winning countless tackles.
Slowly but surely, however, Nottingham Forest began to take charge of the game, Marc Wilson indebted to Robbin Ruiter when he misjudged a long ball and left Murphy running clear. Ruiter was quick off his line to block well, but was well beaten when the 34-year-old went close with a curling effort from distance and a close-range header shortly.
Sunderland's new look front three had frustrated and struggled to buuld up any attacking play, but the goal was a lovely one, McGeady starting the move on the left and playing in Maja. He found Adam Matthews on the left whose audacious cross was headed home by the stooping McGeady.
Matthews had been a menace throughout, a player utterly reborn under Chris Coleman's management.
Forest headed into the break to the sound of boos from their own fans, frustrated with their slow tempo performance.
The second half was a siege, Forest completely dominating the ball and territory but without ever truly carving the visiting side open. Kieran Dowell struck a free-kick sweetly but straight at Ruiter, who then dealt with an attempted chip from Murphy comfortably.
The veteran striker continued to be a menace and the game looked more comfortable for the Black Cats once he limped off shortly after the hour mark.
The Black Cats were not creating chances but by an large keeping the hosts at arm's length. It could all have been so different right at the death, Forest hitting the post with seconds to play, but Sunderland somehow survived.
Three vital points, lifting the side out of the bottom three after their annus horribilis.
Now the task is to draw a line under it in the months to come.