Sebastian Vettel blamed a lack of power from his Renault engine for the massive gap between his third placed Red Bull and the two Mercedes on the front row of the grid for Sunday's Belgian Grand Prix.
The four-time world champion was 2.126 seconds adrift of pole-man Nico Rosberg and 1.898 seconds behind Lewis Hamilton. (Rosberg on pole)
"The reason we're behind is fairly simple," said Vettel. "We know we are down on power. Mercedes can run a bit more wing level, they have more down-force and can still take that wing on the straight - it's the reason.
"Hopefully tomorrow in the race, we will be closer in race pace and closer than the last couple of races." (Also read: Force India struggle in rain-hit qualifying session)
Red Bull team-mate Daniel Ricciardo, who qualified fifth, said Red Bull had run a dry set-up in qualifying because it could not afford to compromise straight-line speed with extra down-force.
The Australian said: "We've set the car up for a dry race so, even though we're typically quite strong in the wet, we knew that our set-up would bring us down to the level of some guys around us.
"The gap to Mercedes was pretty big. We thought we'd be able to close it up a bit in the wet. They were quick straight away, and it hurts a little bit, but it's alright.
"An explanation for now is that we've banked a little bit on a dry race tomorrow so we've set the car up for that. In a nutshell, we've taken down-force off for that.
"With the way our straight-line speed is, we need a chance of fighting, moving forward or defending, and that's why we've gone the way we have."