Aitor Karanka hailed unsung hero Cristhian Stuani after seeing him come from off the bench to help Middlesbrough beat League One side Oxford 3-2 in the FA Cup fifth round.
Stuani's 86th-minute winner at the Riverside Stadium ended the visitors' hopes of a replay after they had fought their way back from 2-0 down.
The Uruguay international's goal against Brighton in the final game of last season secured Boro's return to the top flight and he was on hand once again to earn the plaudits of the Boro head coach.
Karanka said: "He is really important and for me, it's a shame that maybe it is not recognised how good he is and how much he is helping us. His numbers since he arrived here have been amazing, and not just the numbers, the moments.
"Today he appears at the most difficult moment; in the last game [of last season] against Brighton, he scored the most important goal, so for me it's a shame that sometimes he is not recognised as he deserves.''
Boro looked to be coasting when skipper Grant Leadbitter put them ahead from the penalty spot after Stewart Downing had been bundled over by Chris Maguire, and Rudy Gestede's first goal for the club made it 2-0 at the break.
However Maguire, who had seen a first-half strike ruled out for a foul by striker Kane Hemmings at 1-0, pulled one back with a 64th-minute free kick, and when Antonio Martinez levelled seconds later a shock was on the cards until substitute Stuani intervened.
Karanka said: "In this football since I arrived, until the referee says it is finished, always you are afraid because in one minute a League One team can change the game.
"The most important thing today was to win the game, to be in the draw and to realise that three years ago, I don't think anyone could think that Middlesbrough could be in the Premier League and play in the quarterfinals of the FA Cup, so we have to be really pleased.
"I wanted to win the game, I want to be in the semifinals, I want to win to be in the final, I want to win the cup and I want to be in the Premier League next season.''
If Karanka was pleased and relieved on the final whistle, opposite number Michael Appleton was left to reflect on what might have been, and a winning goal which he felt should have been disallowed for a foul on defender Curtis Nelson by Alvaro Negredo.
Appleton said: "There were no issues with the penalty, it was a definite penalty. I thought Stewart Downing was excellent in terms of he was very clever where he took his first touch and he used the pace of Mags [Maguire] trying to get back in, so I have got no issue with that at all.
"But I have a lot of issues with the one we didn't get and then the one they won with, but I'll leave the officials to describe why that was given and wasn't given.
"Negredo was just pinning Curtis Nelson, he was just grabbing his shirt so he couldn't attack the ball and obviously that affected the first contact. They got a little bit of luck, Negredo just got a bit of a nick on it when he tried to do the overhead kick, and to be fair, it was a good finish at the far post.''