For the first time in pre-season testing there was a tussle to be the top driver in Bahrain with Felipe Massa edging Nico Rosberg.
Massa in his FW36 was comfortably leading the way at the lunch break on the penultimate day of testing at the Sakhir circuit. The Brazilian's 1:37.224 was 0.776s up on Nico Hulkenberg's best.
However, it was all change after lunch as Kevin Magnussen came to the fore in his McLaren MP4-29 only to be pipped by the Toro Rosso of Daniil Kvyat.
With an hour left to play, Massa retook the P1 slot with a 1:34.4 only for Nico Rosberg to come flying through, a full second quicker.
Rosberg's lead was short-lived as two minutes later Massa posted a 1:33.258. The Williams driver's time, which was 0.025s quicker than the previous fastest seen in Bahrain during testing, meant he finished the day top of the pile.
Massa was 0.226s up on Rosberg, who had a marathon day with over a 100 laps despite a late start due to an engine change.
Kimi Raikkonen came from behind to finish third but the Ferrari driver was 2.168s off the pace. Magnussen was fourth for McLaren ahead of Kvyat and Hulkenberg. All three were less than three seconds down.
Jules Bianchi, one of the drivers to bring out a red flag, was seventh quickest ahead of Caterham's Marcus Ericsson and Romain Grosjean. The Lotus driver completed just 33 laps before stopping out on the back straight.
Grosjean, though, at least managed more laps than Sebastian Vettel and Adrian Sutil.
Both had issues on their installation laps with Vettel stopping halfway through his - and again later when he attempted another run only to break down in the pit lane - while Sutil's Sauber suffered an engine failure as he came to complete his first lap.
01 Felipe Massa Williams 1:33.258 99 laps
02 Nico Rosberg Mercedes 1:33.484 +0.226 103 laps
03 Kimi Raikkonen Ferrari 1:35.426 +2.168 87 laps
04 Kevin Magnussen McLaren 1:35.894 +2.636 88 laps
05 Daniil Kvyat Toro Rosso 1:36.113 +2.855 81 laps
06 Nico Hulkenberg Force India 1:36.205 +2.947 115 laps
07 Jules Bianchi Marussia 1:37.087 +3.829 78 laps
08 Marcus Ericsson Caterham 1:38.083 +4.825 117 laps
09 Romain Grosjean Lotus 1:42.166 +8.908 33 laps
10 Adrian Sutil Sauber 1 lap
11 Sebastian Vettel Red Bull 0 laps
Day Three's Action In Bahrain