William Gallas claims Tottenham made too many mistakes during their 4-2 humbling at the hands of London rivals Chelsea at the weekend.
Andre Villas-Boas' side showed great character to come from a goal down to take a 2-1 lead soon after half-time.
But they were unable to hold onto their lead and the Blues eventually ran out winners as they picked holes in the Spurs backline - scoring three goals in the final 24 minutes - much to the disgust of the French defender.
And Gallas, who captained Spurs against his former club, believes all the goals were easily avoidable.
"I'm very disappointed because even if I think we didn't start the first half very well, we came back well in the second half," he told Spurs TV.
"We equalised and we scored the second goal, and then I think we made so many mistakes.
"We could not keep the ball in front and it was difficult for us because they had a lot of chances, and they had the occasion to equalise and then to score the third goal. On all the goals we conceded I think we made a mistake.
"When you play against Chelsea you have to be strong for 90 minutes, and we made so many mistakes. We didn't keep the ball very well and they started to play in our half again. They had some chances to score, and in the end we lost 4-2.
"We have to put this behind us. It's difficult to accept it, especially when you play against Chelsea - when it's a derby you always want to win. But we have to forget that game and think about another one."