Kimi Raikkonen set the pace in both sessions of free practice ahead of the Bahrain Grand Prix, with Briton Lewis Hamilton again impressing just behind.
Raikkonen's Ferrari team-mate Felipe Massa finished second in the morning, with Hamilton following Raikkonen home later, while Fernando Alonso was fifth.
Raikkonen said: "The performance of the top teams seems to be very close."
"I was quicker on the long runs, which is a positive, and there is definitely more to come from me," added Hamilton.
"In the first practice, the track was very dirty and slippery so it wasn't until the second session that we began our fine-tuning and completed a couple long run."
"I think I was quicker and more consistent than previously on the long runs, which is positive, and there is definitely more to come"
World champion Alonso had actually led the way midway through the day, but was unable to produce a faster lap and slid down the timesheet as his rivals upped the pace.
He said: "I think we are closer to the Ferraris than we have been so far this season on a Friday. But it's a long weekend so we will see what happens."
Robert Kubica ensured McLaren and Ferrari did not dominate the top three as he captured third place in his BMW Sauber, while Massa was unable to follow on his solid morning display as he finished fourth.
Williams' Alex Wurz improved on his morning session to take sixth place and Nick Heidfeld rounded off a fine day's practice for BMW Sauber as he took seventh.
"The performance levels of the top teams seem to be very close"
Nico Rosberg finished one place higher than he had in the first session in eighth place, while Red Bull's David Coulthard, who finished 20th in the morning, climbed to ninth place. Toyota's Jarno Trulli completed the top 10.
Jenson Button's early season woes continued as his practice session came to an end with just under 30 minutes of the session remaining.
On his 19th lap the Briton struggled with his Honda and after coming off briefly he returned to the circuit only for the rear of his car to suddenly shoot out flames, forcing him off the track.
Super Aguri driver Anthony Davidson finished five places higher than he did earlier in the day as he took 13th place.
Second free practice times:
1 K Raikkonen (Fin) Ferrari 1:33.527
2 L Hamilton (GB) McLaren 1:33.540
3 R Kubica (Pol) BMW Sauber 1:33.732
4 F Massa (Bra) Ferrari 1:33.772
5 F Alonso (Spa) McLaren 1:33.784
First free practice times:
1 K Raikkonen (Fin) Ferrari 1:33.162
2 F Massa (Brz) Ferrari 1:33.679
3 L Hamilton (GB) McLaren 1:33.540
4 R Kubica (Pol) BMW Sauber 1:33.732
5 F Alonso (Spa) McLaren 1:33.784