Tottenham Hotspur manager Ange Postecoglou called his side's collapse against Brighton in the Premier League "probably the worst defeat since I've been here".
Spurs were 2-0 up after 37 minutes and heading for their sixth successive win in all competitions after goals from Brennan Johnson and James Maddison, but conceded three times in the second half as Brighton took the three points.
"It was disappointing and Iâm absolutely gutted with that," said Postecoglou.
"It's an unacceptable second half - we were nowhere near where we should be. Maybe we got carried away with how we were going.
"We kind of accepted our fate and it's hard to understand as we've not done that while I've been here. We usually fight for everything, and when you donât you pay a price."
Spurs missed the chance to go sixth in the Premier League and are ninth with three wins, one draw and three losses from their seven matches.
Postecoglou criticised his side's mentality and spirit, adding: "Maybe things were travelling on too smoothly. Football and life will trip you up if you get too far ahead of yourself and thatâs what it looked like in the second half.
"Itâs a terrible loss for us, as bad as it gets, and thereâs only one way to fix it and thatâs my responsibility.
"We lost all our duels, we werenât competitive and if you're not competitive, irrespective of what you do tactically, it is not going to work."