Tony Pulis admitted his Crystal Palace players were not "at their maximum" in Sunday's 2-0 Premier League defeat to Manchester City.
Edin Dzeko and Yaya Toure scored first-half goals as City reassumed control of their own destiny in the title race on the back of leaders Liverpool losing to Chelsea.
Palace had won five games in a row prior to City's visit, but were unable to cause too many problems for Manuel Pellegrini's men.
"For us to win the game today, every player had to be at their best and you're hoping to catch Manchester City not at their best," said Pulis.
"You have to realise that playing against some teams it's not a level playing field.
"You have a look at the players they've got - Toure being fit (after a thigh problem) was a real big disappointment for me because I think he's a wonderful player and he can do things that can cause havoc.
"He showed glimpses today and when you think he's been out for three weeks and he's come in and done that, it's absolutely wonderful.
"Half the Palace players, they'd have to be honest and say that they never played at their maximum."
Fixtures at Selhurst Park - where Chelsea were beaten last month - could well prove pivotal in the destination of the Premier League trophy, and leaders Liverpool face a visit to Palace a week on Monday.
"There's another game against a fantastic football club in eight days' time," Pulis added.
"(It's) a night game and it will be a great atmosphere here and I just hope the players are on it and we give a real good show, put a real good show on."