Canadian Jacques Villeneuve set the pace for Sauber while Germany's Nick Heidfeld did his best to impress Williams in a wet and windy Formula One test session at Jerez on Thursday.
Heidfeld, living up to his nickname of 'Quick Nick', was second fastest as he wrapped up a test at the southern Spanish track that could lead to either a full race drive or reserve position with Williams.
The 27-year-old did 96 laps with a best time of one minute 22.490 seconds comparing to Brazilian rival Antonio Pizzonia's 1:23.365, according to Williams' timings.
Villeneuve, the 1997 world champion, lapped in 1:22.071.
"I have a good feeling and think I have a good chance," Heidfeld told Germany's RTL television at the southern Spanish circuit. "I've done all I can and I hope it's enough. I must now wait and see what happens."
The German, who raced for Jordan this year after spells at Sauber and Prost, is hoping to beat Pizzonia in the race to partner Australian Mark Webber at the BMW-powered team.
Williams will have an all-new line-up after Germany's Ralf Schumacher and Colombian Juan Pablo Montoya left for Toyota and McLaren respectively.
The team need to find a second driver after failing to secure the services of BAR's Briton Jenson Button.
Pizzonia, the team's test and reserve driver this year after racing with Webber at Jaguar in 2003 before being jettisoned by the Ford-owned team, remains the favourite.
South Africa's Alan van der Merwe, last year's British Formula Three champion, completed 72 laps for BAR as part of a young driver programme and was fifth on the timesheets.
