O’Neill had been bracing himself for the replay on Teesside to be settled by penalties when the former Paris Saint-Germain player popped up to slam home a 113th minute shot to seal his team’s passage into last 16.
“Penalty kicks were a concern because it is a lottery and I obviously thought it was going to go that distance because I thought the teams were tiring so I am pleased from a selfish view-point that it didn’t go to penalties,” O’Neill told reporters at his post-match press conference.
“Stephane picked up a knock at the end and came off and we are hoping it is just cramp and that he does not miss out because he has not missed a game for us this year which is sensational,”
“I think that Stephane is an outstanding player and I am delighted that we have him. He is really great and he hasn’t missed a game this season. That is outstanding and I hope that he does not miss any and that it is just cramp and nothing else.”
O’Neill had Sessegnon to thank for sparing him nerve-shredding penalties as Jack Colback had put Sunderland ahead only for Lukas Jutkiewicz to equalise with his first goal for the Championship side.
“I thought Middlesbrough played very well at our place and I thought this game was going to be hard and so it proved to be,” O’Neill added.
“Over the two games, I haven’t been surprised by Middlesbrough but I am going to stick up for my side, I thought we were the better side.
“It was an exciting enough tie, without there being many clear-cut chances being created. Jack Colback scored a terrific goal and he was brilliant for us, Phil Bardsley was brilliant and Craig Gardner was terrific as well.”
“Arsenal will be pretty pleased that we have gone into extra time and we will try to get ourselves ready for the league game on Saturday and the cup game will take care of itself the week after.”
Middlesbrough boss Tony Mowbray was crestfallen after the game that had seen his team gain the upper hand as the game wore on, but ultimately fall short.
“I am proud of the players but the over-riding emotion is one of disappointment although I’d like to think that over the two games we have shown we could compete in the Premier League,” said Mowbray.
“If we find a way of getting out of the Championship there is no doubt in my mind that we could compete in the Premier League as Norwich and Swansea have shown in that the teams that have gone up have done okay without huge changes.
“We have a very disappointed dressing room because we felt there was a way to get through tonight but we didn’t quite find a way to do it but the team have to keep pushing on.”