Ferrari emerged on top of the final practice session ahead of qualifying for the Spanish Grand Prix after Felipe Massa outpaced team-mate Kimi Raikkonen on Saturday morning at Catalunya.
The Brazilian posted a time of 1min 20.553secs during a session that he led for long periods, while Raikkonen was less than a tenth of a second behind in second place.
Points leader Jenson Button slotted into third place, but he was almost half a second behind Massa's benchmark, which suggests that some of the teams have yet to show their hand ahead of qualifying, with the field behind the Ferrari's being much closer.
Rubens Barrichello in the sister Brawn was fourth ahead of the BMW Sauber of Robert Kubica, while Jarno Trulli, Lewis Hamilton and Timo Glock rounded out the top eight.
For Kubica's team-mate Nick Heidfeld, it would prove to be a frustrating session after he went off at turn twelve half way through and damaged the front left suspension on his car – forcing him to watch on from the sidelines and leaving the team with work to do ahead of qualifying.
He wasn't the only person to have problems, with Raikkonen suffering a spin and Nico Rosberg being forced to take to the exit road at Campsa after running wide. Nelson Piquet also hit an apparent problem with his rear wing which forced him to return to the pits for the team to investigate, with the youngster ending the session in 15th place.