Mauricio Pochettino blamed Tottenham's Christmas fixture schedule for their collapse against Wolves.
Harry Kane had celebrated his new year MBE in style with a stunning goal in the first half that put Spurs ahead.
But the striker's hopes of claiming another medal at the end of the season receded dramatically after the break as goals from Willy Boly, Raul Jimenez and Helder Costa condemned them to a 3-1 defeat.
"THESE ARE THE DAYS THAT YOU WILL NEVER, EVER FORGET!" — Wolves (@Wolves) December 29, 2018
It was Tottenham's third match in seven days over Christmas, and it showed in the second half as Wolves knocked the stuffing out of them.
"We conceded the first goal and the last 20 minutes was tough for the team to find energy, to be competitive, or to try to win the game," said Spurs boss Pochettino.
"I think the game was under control in the first half, I think maybe it was easier than we expected to dominate the game.
"But in the second half we started to feel maybe the game was over, and when you feel the game is over you start to play the way you play, start to decide the wrong way, start to play too many long balls and then was difficult to recover the balls.
"We played more with the heart rather than with the head and we started to spend a lot of energy and of course you need the energy in the end, you miss that.
"I'm very disappointed, like the players, but there's nothing to say. Some games can happen, this type of result, and now we need to move on and be sure we are ready for the next game.
"Today at 1-0, the moment we conceded the first goal the team was down, they started to feel the time, the fixture, everything, and it was difficult to find the energy to win the game."
Kane's afternoon had started well, unleashing a superb strike from 25 yards to put Tottenham ahead, but after Boly equalised with a header the England striker was booked for a dive.
When Jimenez poked Wolves in front with eight minutes left Spurs had nothing left in the tank, and Costa added a late third as the visitors ended a memorable 2018 on a high.
Wolves manager Nuno Espirito Santo said: "I'm very proud. The second half was really, really good.
"We had a lot of belief after the equaliser, I would have said a draw was a good result, but I cannot control the emotions of the boys if they see space in front of them.
"We have achieved something very special in getting to the Premier League and it has been a very special year."
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