Nico Rosberg continued to set the pace in second practice for the Bahrain Grand Prix as Mercedes remained untouchable at the top of the times.
Rosberg's best lap of 1:31.001 put him over two tenths clear of teammate Lewis Hamilton, who had to settle for second place once more.
Both men set their best times with the supersoft tyres.
Jenson Button was a surprising third for McLaren, but the Briton finished 1.2 seconds off Rosberg's pace.
Toro Rosso's Max Verstappen was fourth ahead of Kimi Raikkonen, who was again the quickest of the Ferraris as teammate Sebastian Vettel hit trouble late in the session.
The four-time champion wound up sixth.
Story of the session
Unlike in the first session, Rosberg did not wait long to jump onto the track, the Mercedes driver going for a run on soft tyres eight minutes in.
Rosberg needed just one lap to move to the top, with a time already quicker than the benchmark he had set in the first session.
Hamilton's first run failed to match his teammate's pace, the Briton falling 0.210s short, but the Mercedes pair were still nearly two seconds clear of the field.
Vettel gave Ferrari some hope before the 20-minute mark, however, the German moving up to third place, 0.477s slower than Rosberg.
Massa was the first driver to complete a run with the supersoft tyres, but the Williams man was still seven tenths off the pace.
Teammate Bottas also tried the red-marked rubber and went slightly quicker than Massa to move up to fourth.
Some 35 minutes into the session, however, Mercedes threw down the gauntlet and sent both Rosberg and Hamilton out with supersofts fitted.
Rosberg set a best lap of 1:31.001, a time over 1.5 seconds quicker than last year's pole. Hamilton was again unable to match it, and finished his run 0.241s behind his teammate.
Vettel also went out with supersofts, but the German made a mistake during his flying lap and failed to improve, finishing 1.6 seconds off Rosberg's benchmark.
Button did improve, however, and moved up to third in the McLaren, albeit over 1.2 seconds slower than the Mercedes.
With 15 minutes to go, the virtual safety car was deployed when Vettel's Ferrari hit by trouble.
The German reported he had lost drive and had to park his car, but was later seen tightening what appeared to be a loose wheel nut.
Just a moment later, the VSC was deployed again after Romain Grosjean lost part of his front wing when going over the kerbs at Turn 13.
McLaren rookie Stoffel Vandoorne finished in 11th, seven tenths off Button's pace.