Marco Silva admitted Fulham performed poorly despite a 1-0 opening-day victory at Everton.
The home side missed several chances before Bobby De-Cordova-Reid’s 73rd-minute winner.
“That was not a good performance from ourselves at all,” Silva said.
“I think overall we didn’t perform at our level. After the first 15 or 20 minutes we started to lose so many balls. We gave so many chances for Everton to punish us.
“They had their chances because we gave them so many moments for them to punish us.”
The Whites boss praised keeper Bernd Leno, who produced a number of crucial saves.
Silva said: “Bernd kept us in the game. A great, great performance from Bernd Leno kept us in the game in certain moments when we were under pressure.”