McLaren rookie Kevin Magnussen put in a blistering 1:34.910 to set the pace by 1.5s on the second day of testing at the Sakhir circuit.
While his rivals were lapping in the 1:36s or higher, Magnussen ventured out in the final hour of play to clock a 1:35.4, putting him top of the pile.
He then headed back into the pits before returning to the track for another short run in which he posted a 1:34.910.
That time stood as the one to beat but none of his rivals were able to.
Nico Hulkenberg, Wednesday's pace-setter, settled for second place, 1.535s down while Ferrari of Fernando Alonso was third.
The double World Champion had led the way at midday with a 1:37.700 and did not improve on that for much of the afternoon as Ferrari focused on longer runs.
However, in the final 25 minutes he came through with a 1:36.932 to jump up to third.
Nico Rosberg was fourth quickest on a day that was a bit stop/start for Mercedes as the German brought out the red flags on two separate occasions.
The first was just five minutes into the morning's session while the second was just before midday.
Valtteri Bottas finished Thursday's action in fifth place with Caterham's Kamui Kobayashi making a big improvement in the final five minutes to climb from 10th to sixth. He was, however, still 4.945s down.
Seventh place went to Sebastian Vettel but he won't be too worried because he at least managed to do some laps. He completed 59 laps.
It was Vettel and Red Bull's best day of the pre-season, completing more laps than the team did on all five of the previous days combined.
Vettel's best time was a 1:40.340, which was a massive 5.430s down but at least he was putting in the laps.
Jean-Eric Vergne, another to cause a stoppage, was eighth fastest ahead of Esteban Gutierrez, who also broke down on track.
Romain Grosjean was tenth in the new Lotus E22 while Max Chilton, who had a fuel system problem, completed the timesheets for Day Two.
01 Kevin Magnussen McLaren-Mercedes 1:34.910 46 laps
02 Nico Hulkenberg Force India-Mercedes 1:36.445 +1.535 59 laps
03 Fernando Alonso Ferrari 1:36.516 +1.606 97 laps
04 Nico Rosberg Mercedes 1:36.965 +2.055 85 laps
05 Valtteri Bottas Williams-Mercedes 1:37.328 +2.418 116 laps
06 Kamui Kobayashi Caterham-Renault 1:39.855 +4.945 66 laps
07 Sebastian Vettel Red Bull-Renault 1:40.340 +5.430 59 laps
08 Jean-Eric Vergne Toro Rosso-Renault 1:40.609 +5.699 58 laps
09 Esteban Gutierrez Sauber-Ferrari 1:40.717 +5.807 55 laps
10 Romain Grosjean Lotus-Renault 1:41.670 +6.760 18 laps
11 Max Chilton Marussia-Ferrari 1:42.511 +7.601 17 laps
Gallery: Day Two In Bahrain