Mauricio Pochettino admitted his Tottenham side had missed a big opportunity in the Premier League title race after they were held to a 2-2 draw by Arsenal at White Hart Lane.
The Gunners went ahead through Aaron Ramsey's 39th-minute strike but Spurs turned the tables after Francis Coquelin's 55th-minute red card thanks to quickfire goals from Toby Alderweireld and Harry Kane.
Alexis Sanchez scored with 14 minutes left to salvage a point for Arsenal as Tottenham spurned the chance to pull level on points with leaders Leicester City.
However, Pochettino denied suggestions his young team lacked the maturity to close out the game when leading 2-1 with 15 minutes remaining.
"It's true it was a missed opportunity and the way that we played I believe we deserved more," said Pochettino.
"It was a good game, we showed improvements, and I'm very pleased with the players and how they played the game.
"I think we deserved more. I feel a little bit disappointed and frustrated because we were unlucky with the way we conceded the goal. With 11 against 10 we needed to keep the score the same."
The match had been described as the most important north London derby in 25 years and Pochettino felt Tottenham coped with the occasion despite failing to retain their 2-1 advantage.
"It's not about maturity, it's not about character," he said. "I can give a lot of examples of big clubs with older players who concede goals in the last minutes of games.
"Today, you have to admit the opponent can create good chances, and we were unlucky, but it's not about maturity. Sometimes when you play against 10 men sometimes it's more difficult than when you play against 11.
"Today, if we focus on the result we can feel disappointed we didn't win, but we should feel very proud of our players."
Pochettino still expects plenty more twists and turns in the title race in the closing weeks of the season.
"I think that there are a lot of games ahead - nine games and lots of points," he said.
"It's true we missed a big opportunity but Arsenal are a very good team with very good players and they can create lots of chances. We need to be positive. We are a young team, and we need to be happy."
Coquelin was sent off for two bookable offences and Arsenal manager Arsene Wenger felt Tottenham's Eric Dier should also have received a second yellow card from referee Michael Oliver for pulling back Olivier Giroud.
"I think that the sending off didn't affect the result," said Pochettino. "Maybe Dier could have had a second yellow, yes, but it's always down to the decision of the referee - they are the boss."
Pochettino confirmed Danny Rose came off with cramp in his calf and that he will be assessed on Sunday, although does not expect him to miss Tottenham's Europa League trip to Borussia Dortmund on Thursday.