McLaren completed the hat-trick of fastest times in practice sessions by once again going quickest at the Hungaroring on Saturday morning.

Heikki Kovalainen had been quickest on Friday morning, before his reigning world champion teammate Lewis Hamilton topped the other two sessions that precede qualifying.

However, the third practice is often an unreliable indication of form, given that teams invariably prepare for either the forthcoming low-fuel Q1 and Q2 qualifying segments, or the heavy-fuel Q3 decider.

Championship leader Jenson Button was clearly working on Q3 as he lapped 17th quickest on Saturday, but even so he was multiple tenths slower than the pace of the Red Bulls, who were in the middle of the time sheets.

His teammate Rubens Barrichello was 13th.

"It's about 10C cooler today, and that suits our car slightly better," Red Bull chief Christian Horner told the BBC. "Qualifying is going to be very tight."

Hamilton's margin over the field was a commanding four and five tenths clear of Nick Heidfeld (BMW) and Williams' Nico Rosberg respectively.

Force India's Adrian Sutil ended his final practice session before qualifying in the barriers, having run into the dirt at turns eight and nine.

Qualifying takes place in 90 minutes.