Toby Alderweireld admits Tottenham received a reality check after throwing away their two-goal lead to lose to West Ham in the Carabao Cup.
Spurs were unbeaten in 11 games and arrived at Wembley after thrashing Liverpool in the Premier League and holding Real Madrid to a draw in the Champions League.
But they were undone by a struggling West Ham side that scored three times in the second half to pull off an unlikely 3-2 win.
Andre Ayew scored twice and Angelo Ogbonna's header completed the turnaround after Dele Alli and Moussa Sissoko had put Tottenham in control.
"We were not flying or anything in our heads, but I think it's a good reality check that you still need to work very hard, even if you're 2-0 up, to get results," Alderweireld said.
"You have to keep the level up because if you drop it a little bit you see what happens. It's a good thing to learn.
"Of course we'd love to have won, but we don't have to be too dramatic about it. Next time we have to do better, and we focus on Saturday."
Tottenham visit Manchester United on Saturday in a battle of second against third in the Premier League and they will hope to have Harry Kane back for the trip to Old Trafford.
Kane was rested after going off clutching his hamstring against Liverpool, but the club remain optimistic he will be available this weekend.
West Ham's victory eases the pressure on manager Slaven Bilic, but they must carry the momentum into their own crunch match on Saturday away to Crystal Palace.
Palace are bottom the table while West Ham are 16th, above the relegation on goal difference.
"When you're in a club like West Ham and the results are difficult, the manager is under pressure, and the players are too, but we just need to keep working hard," Ayew said.
"The manager knows the players are behind him and will give everything, not just for him but for themselves too because we have to wear the shirt with pride.
"It's a massive win, but we need to stay calm because we've got a massive game on Saturday."