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 I’m 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 don’t 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 that’s what it looked like in the second half.

“It’s a terrible loss for us, as bad as it gets, and there’s only one way to fix it and that’s my responsibility.

“We lost all our duels, we weren’t competitive and if you’re not competitive, irrespective of what you do tactically, it is not going to work.”

Maddison scored his second goal of the season three days after he had been left out of Lee Carsley’s England squad for the Nations League fixtures against Greece and Finland.

The midfielder called Spurs’ loss “a couple of steps back” after gaining five consecutive victories – against Coventry City in the Carabao Cup, Premier League wins over Brentford and Manchester United and victories in the Europa League versus Qarabag and Ferencvaros.

“Brighton are a good side and have good players but when the first goal went in, in adversity in the Premier League you have got to stay strong and weather the storm. The best teams do that but we definitely didn’t,” added Maddison.

“We just couldn’t deal with the momentum shift. We lost complete control of the game after the first goal went in. We dealt with momentum very poorly when they were coming at us. It felt like it was attack after attack, we couldn’t deal with it and they scored three goals.

“We were saying all the right things of not being complacent, but it doesn’t mean anything if you don’t go out and show it.”

Brighton moved above Spurs into sixth, and manager Fabian Hurzeler said: “My team deserved to win. They worked hard and focused on the things they could control.

“Tottenham always have a great start. They play with intensity and we were not ready for that. We also created chances but defensively we have to improve. We focused on the positive things – the second important thing was to win the duels to build self-confidence. The players worked hard to gain flow and they used it.

“In general I learned nothing new – this is always possible in football. When you are 2-0 down it is not easy, but it was important to stay positive and I’m really happy for the players.”