Felipe Massa got the better of Ferrari team-mate, and Chinese Grand Prix winner, Fernando Alonso to head a 1-2 for the Scuderia during the opening practice session for this weekend's race in Bahrain.
The Brazilian immediately moved to the top of the times as Ferrari emerged with half an hour remaining, edging Alonso's mark by less than a tenth at the end of the 90-minute session as Ferrari again hinted that it may have the car to beat. Just 0.077secs separated the two scarlet machines, but Massa again showed that, not only has he returned to form in the last twelve months, but he retains his long-held affinity with the Sakhir circuit.
Nico Rosberg finished third fastest for Mercedes, having led the way before the Ferrari assault began, and was only a tenth off the pace, but it was a different story for team-mate Lewis Hamilton, who ended the morning down in 13th spot, behind Williams' Valtteri Bottas, as he concentrated on a series of set-up comparisons.
Red Bull had set the early pace, with Sebastian Vettel and Mark Webber running 1-2 at the halfway point, but the world champion - running the latest developments from Milton Keynes - had to settle for fourth spot, 0.303secs off Massa's time, with Webber seventh fastest, another couple of tenths adrift.
Between them, Paul di Resta and Jenson Button gave British fans something to cheer, with the Force India driver claiming fifth spot, a shade over four-tenths off the pace. The Scot was also ahead of team-mate Adrian Sutil – something that has not happened too often this year – with the German filling P8.
The first driver outside the 1min 34s, Button gave McLaren a little more encouragement after his fifth-place result from China, as the Woking team sent both drivers out with an array of sensors on board their MP4-28 in the ongoing efforts to solve its early-season problems. Sergio Perez was eleventh fastest, six-tenths shy of his team-mate, but had no repeat of the incidents that blighted both his Friday sessions in Shanghai.
Behind Sutil, Lotus filled ninth and tenth, but it was not a straightforward session for the Enstone team, with Kimi Raikkonen working on set-up but team-mate Romain Grosjean being hamstrung by KERS issues that meant he wasn't able to get to grips with the new chassis at his disposal this weekend.
Bottas' performance, which saw the Finn sandwiched between Perez and Hamilton, was encouraging for Williams, even though Pastor Maldonado languished further back, trailing the two Toro Rossos. The Venezuelan was ahead of the Saubers, however, the Swiss cars being surprisingly off the pace as Nico Hulkenberg and Esteban Gutierrez brought up the rear of the midfield.
The Mexican rookie was almost within reach of the next man up and, in the absence of Jules Bianchi, that was Charles Pic. The Frenchman shrugged off the presence of Heikki Kovalainen in the other Caterham to lead the way in 'division three', and lapped just over six-tenths shy of Gutierrez's best. Kovalainen was next up as Caterham took advantage of Marussia's altered pairing, but trailed his replacement in the race line-up by a similar six tenths of a second. With Rodolfo Gonzalez for company, Max Chilton was comfortably the faster of the Marussias, leading the erstwhile GP2 backmarker by eight tenths.
Bianchi and Giedo van der Garde will replace Gonzalez and Kovalainen respectively for the afternoon session.