McLaren has taken step closer to Red Bull – Button
The reigning world champion qualified half a second behind pole sitter Mark Webber, but his teammate Lewis Hamilton was only a tenth from the leading RB6.
And the McLarens managed to split the Red Bull pair, although Sebastian Vettel led both Q1 and Q2 and would have been comfortably on pole had he managed to replicate his earlier pace before a brake problem.
Button told reporters: "In Barcelona, the gap to the Red Bulls was almost a second. Here, it's a couple of tenths.
"Red Bull's qualifying pace is what has stood out about them. If we're closer in qualifying, I think we can challenge them in the race."
Hamilton acknowledged that the Red Bulls "still have a performance advantage" over the rest of the field, and team boss Martin Whitmarsh said it showed particularly "in the all-important Turn 8".