Valentino Rossi says he was surprised to struggle for pace in today's Portuguese MotoGP, finishing in fourth place a long way adrift of race winner, Yamaha teammate Jorge Lorenzo.
The reigning world champion was 23 seconds behind Lorenzo and 14 behind Dani Pedrosa, who finished third behind Casey Stoner.
Rossi complained of a lack of rear grip and admits he could not stay with his rivals.
"I thought I could stay with Stoner and Pedrosa, but in the race they took a step forward and there was nothing I could do," Rossi told Italia1 television.
"I was never able to go quick because I didn't have enough grip at the rear. After seven or eight laps I was already struggling, but I constantly lost time even in the opening laps. Today we weren't competitive enough."
Rossi was at least relieved to take the points for fourth place and maintain an 18-point advantage over Lorenzo in the championship.
"We didn't make it, but at least I didn't crash like in Indianapolis last time around," he added. "Now there are three races left on three nice tracks. We must think race by race and go to Phillip Island, which has always been a good track, see what our problems were today and try to do better next time."