Dele Alli feels a combination of "arrogance and overconfidence" led to Tottenham's 2-1 defeat against Manchester United on Wednesday, as Jose Mourinho endured a miserable return to the Theatre of Dreams.
Spurs were billed as favourites before they arrived in Manchester for a crucial midweek Premier League encounter, having secured successive wins over West Ham and Bournemouth over the last fortnight.
Since Mourinho came in to replace Mauricio Pochettino in north London the Lilywhites have rediscovered their best form, but were unable to maintain those high standards against the Red Devils.
The home side took the lead after just six minutes when Marcus Rashford's fierce drive beat Paulo Gazzaniga at his near post, which was a just reward for their bright start to the match.
United had several chances to extend their advantage over the next 30 minutes and were made to pay for their wasteful finishing when Alli produced a superb piece of skill to deceive Fred in the box and fire past David de Gea.
Rashford ended up having the final say shortly after half-time, however, as he won and converted the penalty which ultimately secured a much-needed win for Ole Gunnar Solskjaer's men.
Alli felt Spurs underperformed throughout the 90 minutes, failing to match United's intensity while losing out in personal duels across the pitch.
"It's difficult when you lose to take any positives," the England midfielder said post-match.
"We know what we had to do. We had to match their energy. We lost the game not by them outplaying us - just attitude. We weren't hungry enough and we were slow to every second ball, losing 50-50s.
"Maybe it was a little bit of arrogance and overconfidence. We've been playing well.
"You have to have confidence and arrogance in games like this but have to use it in the right way. We were a bit sloppy but you can't do it in games like this or you'll get punished.
"We've spent a lot of years together. We have to learn from this. Games like this bring your feet back down.
"We want to win any game and you want to win for the new manager at his old place."
Mourinho saw his team slip to eighth in the Premier League standings after his first defeat at the helm, with his former club leapfrogging them into sixth after 15 fixtures.
Spurs will now look ahead to a home clash against Burnley on Saturday afternoon, before travelling to Bayern Munich in the Champions League four days later.
United, meanwhile, have a derby date to prepare for on Sunday as they make the short trip to Etihad Stadium to face Manchester City.