Ange Postecoglou said that "big moments" proved costly for Tottenham Hotspur, whose slim hopes of securing a top-four finish were ended after they were beaten 2-0 by Manchester City on Tuesday.
Erling Haaland struck twice in the second half, while a sensational Stefan Ortega save denied Son Heung-min a certain equaliser in a one-on-one to condemn Spurs to a fifth defeat in six matches.
"It was a tight game decided by big moments - they took them and we didn't," Postecoglou told the official club website.
"It's disappointing. You're not going to create a bagful of chances against City so when they come, you've got to take them.
"I thought we had good control of the game for the most part, limited their opportunities and had some moments ourselves.
"Conceding the first goal was disappointing because there was a lack of discipline there, but after that we had two or three big chances to get back in the game. You've got to take them against opposition like City."
Postecoglou is now demanding a positive reaction from his team, who could slip to seventh if Newcastle United and Chelsea win their remaining two matches and Spurs lose at relegated Sheffield United in their final fixture of the season.
"We've got to put in a strong performance, it's an important game," he added. "We've still got to win the game and then we'll reassess from there."