Jose Mourinho felt fatigue and emotions in his Tottenham team were reasons for West Ham's late fightback as he enjoyed a 3-2 Premier League win at London Stadium.
Goals from Son Heung-min, Lucas Moura and Harry Kane had Spurs cruising in former Manchester United and Chelsea boss Mourinho's first game in charge on Saturday.
But substitute Michail Antonio gave the Hammers hope before Declan Rice had a second goal ruled out for offside, Angelo Ogbonna then scoring from a corner in the sixth minute of added time.
Spurs moved up to sixth in the table by virtue of their first away league win in the league in 13 attempts with Mourinho satisfied by what he saw from his new side after replacing Mauricio Pochettino.
"I was really happy for one," Mourinho said to BT Sport. "Obviously I was very, very happy. We were playing well, bringing to the game things we had tried in training.
"We spoke a lot about it. I was really happy. And we had [the chance to make it] 4-0 and kill the game.
"We are lucky I have so many years in the Premier League that I told the players at half-time, 'Even if we are 3-0 in the 85th minute the game will still be open'. I think they understood that.
"But for the last 20 minutes, of course, fatigue, people coming from national teams, all the emotions of losing the manager, another one comes, start working with me.
"Clearly fatigue in the last 20 minutes and also a reaction from a very good team and very good players. The coach tried different things, they were being more direct, putting the ball in our box and creating pressure.
"It was not easy, but I liked very, very much our first 60 minutes. Not just happy with the work, but also enjoying.
"The most important thing in the end was not to win 3-0 or 4-0 or play wonderfully, no matter how, the three points were most important for us. Maybe also the mental barrier of so many months without an away win was important.
"The boys are happy and that's what I really wanted. I wanted them to be back to happiness and there's nothing better than winning a football match, let me tell you."
Dele Alli lost form in the latter period of Pochettino's era but the England midfielder, who has slipped out of favour for the Three Lions, helped to create the second Spurs goal with a fine piece of improvised individual skill.
"I'm happy with everyone but if you ask me if I'm happy with Dele, then yes," Mourinho said. "I spent a few minutes with him in training and in social life, outside the pitch.
"The best Dele has to be back. He's too good not to be in the national team, he's too good not to be an important player for Spurs, he's too good not to be one of the best players in the world.
"He has to start from now, hopefully, without injuries, hopefully with some stability, also from a tactical point of view. He's a fantastic player. I'm happy he's here."