Australian GP, 2 April. Start: 0500 GMT
Honda test driver Anthony Davidson set the pace in both practice sessions for Sunday's Australian Grand Prix at Melbourne's Albert Park.
Davidson put in a strong display around Albert Park
Davidson took advantage of his only action of the weekend to set a best time of one minute 26.822 seconds.
That put him clear of Williams' Alex Wurz and BMW Sauber's Robert Kubica.
But Davidson's Honda team-mate Jenson Button was the fastest race driver in fourth, beating world champion Fernando Alonso by 0.230secs.
Button admitted he struggled in an untidy session which saw him bounce through the gravel twice, including an embarrassing off on his first lap out of the pits.
"It's really difficult out there, it's really low grip, you can see a lot of people are making mistakes," he said.
"I don't think I took any corner the same on any lap because it's so difficult to drive out there.
"I went off because there is such low grip, I was going slow at the time and went through the gravel which is quite unusual for me.
"Hopefully the circuit will get better but we are looking at things to help our consistency."
Alonso refused to read too much into Button's slip-ups and picked out the Briton as his main rival for Sunday's Grand Prix.
"He never makes mistakes and competes in all circumstances," the Spaniard said.
"I think Jenson can do really well and his car is now very competitive.
"We all saw him in 2004 when he was third (in the championship) behind the two Ferraris and had lots of podiums and that showed he has to be a consistent driver."
Alonso was ominously up at the sharp end straight away
Michael Schumacher was sixth for Ferrari with McLaren's Kimi Raikkonen just behind him in seventh but David Coulthard spun on his way to 13th for Red Bull.
Schumacher also suffered an off-track excursion, although he blamed the wind rather than the parkland circuit.
He said: "It made for unpredictable handling. On one lap I ended up running a bit wide in a corner when a gust of wind pushed the car from behind."
Scuderia Toro Rosso test driver Neel Jani lasted only a few minutes before problems struck in the first session.
The Swiss driver lost control of his car under-braking for turn nine, hitting the wall and coming to rest in the gravel.
His team-mate Vitantonio Liuzzi almost repeated the feat in the opening minutes of the second session but the Italian escaped with just a trip through the gravel.
In this morning's first session, Davidson was again the pace-setter, leaving his best lap to the final seconds of the hour.
Davidson's lap of 1:28.259 put him 0.300 seconds clear of Red Bull counterpart Robert Doornbos, who spun late in the session.
Jacques Villeneuve, one of only three racers to clock more than 10 laps, was third fastest in his BMW-Sauber.
But the 1997 world champion will lose 10 places on the grid after he needed a new engine following practice.
Combined times from Friday's two practice sessions at the Australian Grand Prix:
1 x-Anthony Davidson (GB) Honda one minute 26.822 seconds (136.630mph)
2 x-Alexander Wurz (Aut) Williams-Cosworth 1:26.832
3 x-Robert Kubica (Pol) BMW Sauber 1:27.200
4 Jenson Button (GB) Honda 1:27.213
5 Fernando Alonso (Spa) Renault 1:27.443
6 Michael Schumacher (Ger) Ferrari 1:27.658
7 Kimi Raikkonen (Fin) McLaren-Mercedes 1:27.773
8 Rubens Barrichello (Brz) Honda 1:28.075
9 Juan Pablo Montoya (Col) McLaren-Mercedes 1:28.200
10 Felipe Massa (Brz) Ferrari 1:28.227
11 Giancarlo Fisichella (Ita) Renault 1:28.280
12 Jacques Villeneuve (Can) BMW Sauber 1:28.440
13 David Coulthard (GB) Red Bull-Ferrari 1:28.531
14 x-Robert Doornbos (Mon) Red Bull-Ferrari 1:28.559*
15 Mark Webber (Aus) Williams-Cosworth 1:28.860
16 Nick Heidfeld (Ger) BMW Sauber 1:29.053
17 Jarno Trulli (Ita) Toyota 1:29.138
18 Scott Speed (USA) Toro Rosso-Cosworth 1:29.196
19 Ralf Schumacher (Ger) Toyota 1:29.379
20 Christian Klien (Aut) Red Bull-Ferrari 1:29.601*
21 Tiago Monteiro (Por) Midland-Toyota 1:29.713
22 Nico Rosberg (Ger) Williams-Cosworth 1:29.933
23 x-Neel Jani (Swi) Toro Rosso-Cosworth 1:30.686
24 Vitantonio Liuzzi (Ita) Toro Rosso-Cosworth 1:30.734
25 Christijan Albers (Ned) Midland-Toyota 1:30.830
26 x-Markus Winkelhock (Ger) Midland-Toyota 1:31.260
27 Takuma Sato (Jpn) Super Aguri-Honda 1:32.556
28 Yuji Ide (Jpn) Super Aguri-Honda 1:34.224
x = test driver not eligible to race; * = time set in first session