Newcastle's Alexander Isak scored a dramatic stoppage-time winner at Nottingham Forest from the penalty spot to keep their hopes of a top-four finish firmly alive.
Isak, who had earlier cancelled out Emmanuel Dennis' opener in the first half, coolly placed his spot-kick into the right corner after Moussa Niakhate was penalised for handball in the box.
In an eventful encounter, Newcastle substitute Elliot Anderson thought he had made it 2-1 when he thumped in a header at the back post, only for it to be ruled out by VAR for offside in the build-up.
Newcastle were on top for large spells and hit the crossbar twice in the first half, either side of a glorious chance fired over by Joe Willock from close range.
Forest's opener came against the run of play when Newcastle defender Sven Botman unforgivably gifted possession to Dennis, who smartly chipped it over the players standing guard on the goalline.
The visitors' pressure eventually paid off when Willock set-up Isak for a precise volley into the far corner on the stroke of half-time and the Swedish striker later delivered the winner to spark celebratory scenes in the away end in Nottingham.
Newcastle boss Eddie Howe later said: "There was a lot in that game it was action packed.
I thought we did enough to win. I think there was a spell where we lost control in the first half. Apart from that we were the dominant team didn't deserve to go behind but delighted to win it is a big three points.
"Whenever you come back it is a satisfying feeling and to score that late is another boost i think today was always going to be difficult but i think we deserved it.
"There was a spell where we lost our way and got a bit emotional the goal rocked us apart from that we created chances. The character shown in the group was fantastic.
"I saw the arm go up and the ball hit the arm for me that is a stonewall penalty.
"Alexander Isak took our last penalty and scored it really well Kieran Trippier is an incredible penalty taker but Alex is our designated taker and he took it really well.
"It was a difficult experience the cup final because we were desperate to win but the players have responded brilliantly.
"The fans never disappoint and they were a feature in the game which is rare for the away crowd."