Mousa Dembele has said Tottenham cannot afford to lose points against "small" teams like West Ham if they are to mount an assault on the top four this season.
Spurs were beaten 3-0 by the Hammers at White Hart Lane on Sunday to halt a fine start in the Premier League following the recruitment of seven summer signings at a cost of nearly 100 million pounds.
And Dembele has said there cannot be any more slip-ups against supposedly inferior opposition.
"If we want to be there with the top four we need to win these games," he said. "You see the top teams, if they want to be champions, they have to win these small games. You can see it's the difference with the guys who become champions -- they win these small games.
"It's easier to play against the top teams for the motivation -- but if we want to be a top team we need to be concentrated for these kind of games.
"It's a mental thing. We have a lot of players and you can change the team very quickly, so everyone needs to know it's a difficult season."
West Ham's victory in North London was their first against Spurs in 14 years, and their biggest at White Hart Lane since 1994.