Jenson Button was disappointed with fifth place in Sunday's British Grand Prix at Silverstone but insisted there was nothing more he could do.
His BAR-Honda, which started second on the grid, was no match for the McLarens or Renaults, finishing 40 seconds behind winner Juan Pablo Montoya.
"You're never going to be that happy with fifth but I can't expect any more really," said Button.
"The top two cars are just staggering in terms of performance."
The Briton added: "Watching them through Becketts and Copse corners, the difference is just another world, so I'm a tiny bit worried for the rest of the year."
Button's result pushes him up to 12th in the drivers' championship with nine points, 69 points behind leader Fernando Alonso, who finished second for Renault.
The BAR driver was initially impressed with his pace in qualifying, believing he was on a similar strategy to the cars around him.
However, he was surprised to find out the McLarens and Renaults could run longer in the race.
"Before the first pitstop I thought we'd be stopping on the same lap, but in the end we stopped earlier. Then after that they just disappeared," he said.
Button looked set for fourth midway through the race but lost time trying to lap backmarkers and felt that the marshals did not do their job of waving the blue flags correctly.
Alonso also criticised the marshals for failing to alert the slower cars that the leaders were coming through.
Button said: "The blue flags were pretty awful. They just weren't coming out.
"It probably didn't cost me too much because it was the same for everyone. But it's not up to the usual standards."