Williams F1 driver Nico Rosberg set the fastest time in practice for the Bahrain Grand Prix.
The Williams man's 1m33.339s lap was nearly two tenths faster than Renault's Fernando Alonso could manage, while Jarno Trulli (Toyota) ended the day third quickest.
Jenson Button (Brawn) was sixth fastest, while Lewis Hamilton (McLaren) was 11th, after going fastest in the - generally slower - opening practice session.
Last weekend's winner Sebastian Vettel and his Red Bull team-mate Mark Webber moved into contention with fourth and fifth in the last 15 minutes of the season.
Ferrari's struggles continued: Felipe Massa was 16th, while Kimi Raikkonen was 18th.
1 Nico Rosberg (Williams-Toyota) 1m 33.339s2 Fernando Alonso (Renault) +0.191s3 Jarno Trulli (Toyota) +0.277s4 Sebastian Vettel (Red Bull-Renault) +0.322s5 Mark Webber (Red Bull-Renault) +0.337s6 Jenson Button (Brawn-Mercedes) +0.355s7 Adrian Sutil (Force India-Mercedes) +0.424s8 Timo Glock (Toyota) 1:33.764 +0.425s9 Rubens Barrichello (Brawn-Mercedes) +0.546s10 Kazuki Nakajima (Williams-Toyota) +0.560s11 Lewis Hamilton (McLaren-Mercedes) +0.655s12 Giancarlo Fisichella (Force India-Mercedes) +0.686s13 Sebastien Buemi (Toro Rosso-Ferrari) +0.788s14 Sebastien Bourdais (Toro Rosso-Ferrari) +.027s15 Nelson Piquet (Renault) +1.072s16 Felipe Massa (Ferrari) +1.225s17 Robert Kubica (BMW-Sauber) +1.266s18 Kimi Raikkonen (Ferrari) +1.331s19 Heikki Kovalainen (McLaren-Mercedes) +1.425s20 Nick Heidfeld (BMW-Sauber) +1.451s