Tottenham head coach Mauricio Pochettino hailed Christian Eriksen's "big, big potential" after the Dane's late winner sealed a 2-1 victory against Sunderland.
Jan Vertonghen's deflected shot gave the hosts a third-minute lead, but the visitors equalised through Sebastian Larsson's superb free-kick, won by former Spurs man Jermain Defoe on his Black Cats debut.
Larsson's strike looked to have earned the Black Cats a valuable point, but Eriksen added a late twist when his placed shot from edge of the area went in off a post with two minutes remaining.
It was the 22-year-old's eighth goal in the Barclays Premier League this season.
"I am happy for Christian," Pochettino said.
"He is still young, but he has big, big potential. He improves every day. I am happy for his performance.
"His contribution is clear. I am happy because he is a very good guy, a good professional and a great player."
Tottenham, who climbed to fifth, should have had a third goal in injury-time, but Vertonghen's effort was wrongly ruled out for offside.
Sunderland goalkeeper Costel Pantilimon had gone up for a corner and, as Tottenham broke with speed, Vertonghen was still in his own half when the ball was played to him.
"I think the referee and the linesman were a little bit confused about the rule," Pochettino said.
"When the pass went to Jan, it was before he had got into the opponents' half.
"It was a quick action, maybe the referee was focusing on another part of the game, sometimes it happens to me.
"It was difficult though because it was 2-1 and it could have decided the game. Maybe I can be in a different mood about it now."
Pochettino added: "Jan is upset because he does not have many opportunities to score and the action was like that of a striker.
"It is difficult to understand why, but we are all human and we can all make mistakes."
Tottenham have earned 10 points this season with goals in the 88th minute or later and Pochettino believes those returns are down to his players' fitness and never-say-die mentality.
"Our fitness is very good," Pochettino said.
"The club believes that is very important - the sports science and medical staff have done a great job so far.
"And also our mentality. In football you always need to believe. You need to be strong in your mind and you have to always believe it is possible to win the game."
Eriksen's decisive contribution ensured an unhappy return to White Hart Lane for Defoe, who had previously scored on each of his club debuts.
Defoe struggled to make an impact against his former club before being substituted in the 74th minute, although the 32-year-old could have won a penalty when he tumbled over Vertonghen's planted leg in the first half.
"He started brightly, he was sharp," Sunderland manager Gus Poyet said.
"If he got the penalty and he scores we're talking about a great debut.
"The referee, though, didn't see what everybody else saw clearly.
"He was looking for his chance and I played him a bit longer than expected.
"He will get better and better and when he gets that first chance he will put the ball in the back of the net.
"It was a good start and a great place for him to start playing for us."
Sunderland remain 16th in the table, one point above 18th-placed Hull, who play West Ham on Sunday.
"When the winning goal is so late, it hurts," Poyet added.
"But it is part of football, you have to be good until the last minute, not the 88th or the 89th."