Felipe Massa topped the timesheets at lunch on the penultimate day of pre-season testing as a supersoft tyre run saw him clock a 1:23.262.
It was the perfect start to the penultimate day for all nine teams as they covered lap after lap without any red flag stoppages.
With the sun shining down on the Barcelona track, Massa's 1:23.262 saw him finish 0.014s up on Ferrari's Kimi Raikkonen.
Behind him, Marcus Ericsson put in a late run on the supersofts to nab third place ahead of Nico Hulkenberg.
The German was once again behind the new Force India VJM08 and was the busiest driver out on track as the team tried to make up for lost time.
Hulkenberg completed 76 laps with a best time of 1:24.939.
Kevin Magnussen was fifth quickest as he filled in for Fernando Alonso at McLaren. He amassed 38 laps on his debut run in the MP4-30 as McLaren continued to put the mileage on the car.
Lewis Hamilton was sixth but the Brit has yet to launch an attack on the timesheets and all eyes will be on him in the afternoon to see if he copies Nico Rosberg's achievement from Day Two.
Daniel Ricciardo, Carlos Sainz Jr and Romain Grosjean completed the timesheets.
01 Felipe Massa Williams 1:23.262 45 laps
02 Kimi Raikkonen Ferrari 1:23.276 0.014 51 laps
03 Marcus Ericsson Sauber 1:24.477 1.215 50 laps
04 Nico Hulkenberg Force India 1:24.939 1.677 76 laps
05 Kevin Magnussen McLaren 1:25.225 1.963 38 laps
06 Lewis Hamilton Mercedes 1:25.471 2.209 36 laps
07 Daniel Ricciardo Red Bull 1:25.742 2.480 60 laps
08 Carlos Sainz Jr Toro Rosso 1:26.330 3.068 53 laps
09 Romain Grosjean Lotus 1:27.950 4.688 44 laps