Casey Stoner fears he will not be quick enough to fight for race victory in Qatar after chattering issues afflicted his Honda in qualifying.
The Australian has four wins and three poles to his name at Losail, and was quickest in this weekend's first two practice sessions, but saw Jorge Lorenzo's Yamaha beat him to pole on Saturday night.
Stoner said it was not just a case of Lorenzo being slightly faster in the session, but a sign of a worrying problem for Honda, which has grappled with chattering in winter testing.
"To be honest, I'm disappointed," said Stoner. "We started the weekend in a bit of a bad situation. We've basically gone full circle and come back to it.
"The first part of this session and last night's session, we were pretty happy with where the bike was. We had a couple of issues last night, but I got the bike working pretty well and was quite happy with it.
"In the early part of this session, everything seemed to be going quite well, and then every time we tried to improve the bike we just made it worse and worse.
"We've got the shattering issue back in huge amounts, and as soon as we put the soft tire in it just doubled what [problems] we had because of the extra grip.
"It's something we've found whenever we've put new tyres on - the chattering would get a little bit worse, then we'd slowly try to weed it out, and we got to a point where we were happy, but we've gone full circle and come back round to where we were."
The reigning MotoGP champion is concerned that it will not be possible to fully resolve the problem before Sunday night's race.
"We've got a lot of work to do tonight," said Stoner. "We're going to have to go across everything that we did over these last few days and try and come up with something.
"We need something for the warm-up before the race tomorrow, otherwise it's going to be a long hard slog with this bike."