Mauricio Pochettino admits his Tottenham side lacked 'energy' as they fell to a 3-1 home-defeat to Wolverhampton.
The Spurs boss insisted the heavy festive schedule has caught up with his players after Nuno Espirito's men beat The Lilywhites on Saturday afternoon. It was their third tie in the last seven days and they failed to make it their sixth league-win in a row.
"That is football," Pochettino told Sky Sports after the match at Wembley. "Sometimes it is very difficult to explain. In the first half we dominated, had lots of chances and controlled the game.
"In the second half we started to feel the effort from [the amount of] fixtures and everything. We needed more energy.
"You need to play not only with quality but with energy and it was difficult to find energy. We miss that fresh energy that we needed to find the second goal. We were a little comfortable because they played so deep. When you don't kill the game, in a period when it is so tough to play every three days, it is tough."
The Argentine added: "The Premier League is so tough to play. Any team can beat you. We drop a little bit in our focus and our concentration in the last 20 minutes.
"This period is so tough. It is not easy for the player to compete at their top level. I need to back them and we go again for the next game."
This was Mauricio Pochettino's first ever Premier League defeat against a newly-promoted side while in charge of Spurs - the Argentine was unbeaten in 27 such meetings before today (W25 D2).
Wolves recorded their first Premier League win over Spurs since February 2010 (1-0 under Mick McCarthy), having gone winless in their previous five meetings in the competition (D2 L3).
This was only the third time that Spurs have lost a Premier League home game by 2+ goals under Mauricio Pochettino - the other two were against Liverpool (0-3 in August 2014) and Manchester City (1-3 in April 2018).
Spurs suffered a Premier League home defeat after opening the scoring for the first time since May 2016 (1-2 v Southampton).
Wolves have only lost two of their seven Premier League games against 'big six' opponents this season (W2 D3 L2), managing to avoid defeat in each of their three away games (W1 D2).