Lewis Hamilton says it would be a "miracle" if he wins Sunday's Hungarian Grand Prix despite qualifying on pole.
Hamilton heads Red Bull's Sebastian Vettel and Lotus's Romain Grosjean but fears his Mercedes will again suffer with the tyre problems that have blighted their season.
"We are in a good position but I don't envisage it being a win," he said.
"We've got a steep hill to climb with these tyres in these [hot] conditions. If we did win it would be a miracle."
Hamilton said he felt the Pirelli tyres, which are designed to wear out quickly so as to ensure the teams have to make multiple pit stops, were holding back Mercedes' performance.
"We've got a good car so if we didn't have the tyre issues we'd be able to compete with these guys in the race," he said.
"It sucks that I'm not able to race with these guys but we'll do what we can."
The Mercedes has tended to overheat its rear tyres, with the result that Hamilton and team-mate Nico Rosberg, who has qualified fourth, fall back through the field during the race.
Rosberg said the indications from practice in Hungary were that the new design of tyre that has been introduced for this race was going to lessen the problem.
But Hamilton said: "I don't have any indications it's going to be better. It didn't feel great yesterday (in Friday practice when the teams do their race-simulation runs) but I'm hopeful it will be better."
Hamilton has won three times at the Hungaroring, but said he was not confident he could do so again.
"I've been very lucky to win here," he said. "It's a great track, it's very demanding, technically, on the car and with the heat.
"As a driver it is non-stop. Going into (the race) I definitely don't have the same confidence as I had when I won the previous races here for obvious reasons with the tyres but maybe Nico's right. Maybe we will have a better chance.
"Statistics show the Red Bull is 0.5-0.8secs a lap faster than us on the 'prime' tyres over a long run, so with those stats there is nothing really you can do.
"We just have to try to maximise every second we get out there and I'd really love to be able to remain in the fight.
"It's just the way the sport is at the moment.
"It's a shame that tyres are the decider because the team has done such a great job to build such a competitive car and I honestly feel it is just as competitive in terms of downforce and mechanics in the race as the Red Bull, it's just the tyres.
"We built those things on and they just don't work for us."
Hamilton's pole was his third in a row this season but he said he felt he could have gone even faster.
"I was saying to Nico that it really didn't feel like a good lap so I was really surprised when I looked at the onboard and it looks like a reasonably tidy lap," he said.
"But it didn't feel good so I thought it wasn't good enough. I'm delighted it was, happy I could put the team on the front row and my brother texted me and said that's my 30th pole so I'm quite happy with that as well.
"I don't feel like I made any mistakes; I just don't feel like I extracted the most from the lap.
"There's a couple of areas, particularly Turn Six, where I felt I lost a bit on the braking, and the middle sector wasn't bad, it was OK, but it didn't feel like it was really on the limit and then the last two corners felt really poor.
"I really feel there is a lot more in the car. I feel like I could have had another couple of tenths or so. I felt that in the last race as well."
Vettel and Grosjean are expected to be the leading contenders for victory, with perhaps a challenge coming from the German's title rivals, Ferrari's Fernando Alonso and Lotus's Kimi Raikkonen, who start fifth and sixth.