Juande Ramos admitted his UEFA Cup hat-trick hopes are in the balance after Tottenham were given a reality check by PSV Eindhoven at White Hart Lane.
The Dutch champions and league leaders will protect a 1-0 advantage next week after Gilberto's blunder gifted Jefferson Farfan the winner in the first leg of the last-16 clash on Thursday night.
It was the second defeat in a row since the Carling Cup victory over Chelsea and dented Ramos' hopes of winning the UEFA Cup again after lifting the trophy with Sevilla in the last two years.
"You could say that it was a reality check," the Spaniard said. "Against Birmingham at the weekend and now PSV we haven't played as well as we could have. We have lowered our tempo."
Ramos said before the clash that PSV would provide the barometer of his side's chances in Europe.
"The barometer is very low," he said. "If we want to go through we have to improve.
"It's true, we had our best 11 players out there and were disappointed as PSV were better."
Ramos refused to blame Gilberto but the Brazil full-back was at fault for Farfan's 34th-minute strike, losing the ball before the Peru forward smashed past Paul Robinson.
Jamie O'Hara was brought on for Gilberto at half-time to cap a miserable debut for the January signing from Hertha Berlin.
"I didn't substitute him because he made a mistake," Ramos insisted. "It was because he has been injured and he needed rhythm.
"Every footballer makes mistakes, what we have to do is support him and try to help him recover. We don't blame him for the defeat."
The night got worse for Ramos when Jermaine Jenas twisted an ankle in the second half and was carried off on a stretcher.
PSV could have extended their lead but Robinson pulled off a stunning save to deny Farfan.
"Of course I didn't like the result but we still have a second leg and when you lose by one goal it's not too bad," Ramos said. "But we have to play much better game.
"After this it's going to be very difficult and we are going to have to improve if we want to go through.
"They played better than us, they are very good - first in the Dutch league with a lost of points advantage, and have come from the Champions League."
PSV boss Sef Vergoossen was cautious despite his team's impressive performance.
"We're very happy," he said. "It's very good to take that into the second leg but there are no guarantees. We played well in the second half and 2-0 was closer than 1-1 ever was.
"I was hopeful before but you never know, people have to do their jobs on the pitch."