Lewis Hamilton set the pace on a sunny penultimate day of testing at Barcelona, edging Felipe Massa by seven-tenths.
The Mercedes driver pulled away from the chasing in the morning's session when he clocked a 1:20.558 on the soft Pirelli tyres.
Leading the way at lunch by more than a second ahead of Adrian Sutil, Hamilton's advantage was cut in the afternoon when Massa posted a 1:21.266. That, though, was still 0.708s short of Hamilton's best.
Sutil, who is making his return to the Formula One grid after being re-signed by Force India, remained third despite not improving his lap time while Pastor Maldonado was fourth.
The Venezuelan edged his Williams team-mate Valtteri Bottas by 0.163 seconds. The team-mates shared the driving duties on Saturday with Maldonado in action in the morning before handing the FW35 over to Bottas for the afternoon.
Sauber's Esteban Gutierrez was sixth quickest and the last driver to get within two seconds off Hamilton's best while Mark Webber and Sergio Perez completed the top eight.
There were three red flag stoppages on Saturday; the first belonging to Giedo van der Garde when a "mechanical issue" forced the Dutch driver to park his Caterham at Turn 6.
Davide Valsecchi, who was filling in for the ill Kimi Raikkonen in the morning, stopped an hour later at Turn 3. He handed the car over to Romain Grosjean for the final two hours of testing with the duo finishing the day 11th and 10th respectively.
The final red flag came in the last 30 minutes of testing when Massa lost a front left wheel on the approach to Turn 10.
The day also saw Jules Bianchi make his Marussia debut. He finished second from last, 3.470s off the pace, but - more importantly - he was ahead of the Caterham of van der Garde.
01. Lewis Hamilton Mercedes 1:20.558 117 laps
02. Felipe Massa Ferrari 1:21.266 94 laps
03. Adrian Sutil Force India 1:21.627 109 laps
04. Pastor Maldonado Williams 1:22.305 34 laps
05. Valtteri Bottas Williams 1:22.468 31 laps
06. Esteban Gutiérrez Sauber 1:22.553 99 laps
07. Mark Webber Red Bull 1:22.658 59 laps
08. Sergio Perez McLaren 1:22.694 101 laps
09. Jean-Eric Vergne Scuderia Toro Rosso 1:23.223 114 laps
10. Romain Grosjean Lotus 1:23.380 46 laps
11. Davide Valsecchi Lotus 1:23.448 16 laps
12. Jules Bianchi Marussia 1:24.028 74 laps
13. Giedo van der Garde Caterham 1:24.235 126 laps
The Penultimate Day Of Testing