Toto Wolff was blown away by Ferrari's speed advantage over his Mercedes Formula One team on Saturday after Charles Leclerc and Sebastian Vettel secured a front row lockout for Sunday's Belgian Grand Prix.

Leclerc grabbed his third pole of the year with a lap that was seven-tenths of a second faster than the best from teammate Vettel, leaving Lewis Hamilton third ahead of fellow Mercedes man Valtteri Bottas.

"It's 1.3 seconds to Leclerc. We knew it would be difficult and probably third and fourth was what we expected as the optimum result," said Mercedes head Wolff.

"I think it could have been second, but if we have (power) deficit anyway with our package. That (deficit) is enormous and the power is just ridiculous from Ferrari on these kind of tracks.

"You have just got to do everything right -- and we didn't do that today."

Wolff's disappointment followed a session in which the Mercedes pair almost collided during their warm-up laps for the third round of qualifying as they jostled for slip-streaming positions ahead of their 'hot laps'.

"Of course, we know that the 'tow' is important, but today we tripped over our own feet," he said.

"You want to do it extra perfect and then you are looking like an idiot. And this is what happened twice today."

but then the cold probably gives them an advantage.

"The straight line speed ... They haven't got it available like they have in qualifying. It's a totally different ball game."

Despite his frustration, he said he was still optimistic about Sunday's race.

"I think there is everything to play for tomorrow. We have a strong race car and we know that they have suffered more in the races."

Reigning champion Hamilton, who forced his team into two hours of repairs after a heavy crash in Saturday morning's final practice session, said he was nonetheless happy to qualify on the second row.

"It's so painful because you know many people work so hard to build those parts and how hard the guys work to put the car together -- and I knew that it was going to be a tough challenge," he explained.

"I was just trying to pay them back with a good qualifying so considering I missed all of P3 -- and a lot of P1 too actually -- I am grateful to be up here."

After eight wins from the opening 12 races this year, the five-time world champion has a comfortable 62-points lead ahead of team-mate Bottas in the drivers' championship with nine races to go.