McLaren's Lewis Hamilton on Saturday said Red Bull were hurting badly from a ban on a key piece of technical gear after they lagged in Malaysian Grand Prix qualifying.
Hamilton, who took his second successive pole position, said the outlawing of so-called "blown diffusers", which channel exhaust fumes to increase downforce, had clearly damaged the reigning constructors' champions.
While Hamilton and his team-mate Jenson Button occupied the front row for the second weekend running, Red Bull's Mark Webber and Sebastian Vettel, who is seeking his third straight world title, will start from fourth and fifth.
"It's quite clear that last year they had a huge advantage with the blown diffuser and they don't have that now. Everyone's a lot more equal," Hamilton said.
The 2008 champion has started the season strongly after a miserable 2011, and at Sepang he was quickest in two of the three practice sessions before taking pole with a lightning early lap in the final qualifying segment.
However Button, who won last week in Australia ahead of Vettel with Hamilton third, warned the gap between the first five on the grid, about four-tenths of a second, was too close for comfort.
"It's small, it's not the advantage that we've seen over the last couple of years," Button said. "And the race is a very different thing, I think they proved that in the last race.
"Obviously Sebastian got a bit lucky with the safety car (in Australia) but still, their pace was good in the race so we expect that again."
Last week in Melbourne, Hamilton was running behind Button until a timely safety car intervention allowed Vettel to snatch second place.