Antonio Conte acknowledged Tottenham must do better in big games after they were beaten 2-0 at Manchester United.
Goals from Fred and Bruno Fernandes condemned Conte's side to only their second Premier League defeat of the season, having also been beaten 3-1 at leaders Arsenal earlier this month.
Spurs have made an otherwise impressive start to the campaign and still sit third in the table, level on points with second-placed Manchester City and three ahead of Chelsea in fourth, albeit having played a game more than both.
However, speaking to Amazon Prime, Conte pointed to the difference in spending power between his club and United, who forked out more than anyone in England in the last transfer window to bring in the likes of Casemiro, Lisandro Martinez and Antony.
Spurs also spent money on Yves Bissouma, Djed Spence and Richarlison among others, but the Brazilian was unable to feature at Old Trafford due to injury.
"I consider United a really good team," Conte said. "You know very well the potential of this club, what they did in the transfer market and what money they can spend. For sure, we are speaking about two different levels.
"At the same time, I think in this type of game we can do much better.
"We are struggling. We struggled against Chelsea, we struggled against Arsenal, we struggled today against United."
Spurs conceded 28 shots on their goal from the hosts, including 19 in the first half, while managing only nine of their own all game, with just two on target.
"United deserved to win, they played a really good game," Conte conceded.
"For our side, in this type of game when the level has got to be high, we need to improve a lot. We have to try to be better than today."