Stoner won his first BMW sports car at the 2007 Valencia season finale, when he wrapped up the best qualifier of the season award, and the Australian picked up where he left off at a wet Jerez.

Casey instantly stamped his authority on the slowly drying track, literally overtaking title rival Valentino Rossi in the early stages before pulling a huge 3.2secs clear of the competition after just five laps.

Stoner then sat calmly in the pits, with his arms crossed, to see if anyone could get near his mark. They couldn't, but Stoner returned to the track for the final five minutes just in case, by which time his lead was still 1.5secs, now over countryman Anthony West.

The closing stages saw Nicky Hayden, and then Rossi, emerge as best of the rest behind Stoner - but the seven-times world champion, riding with Bridgestone tyres in the wet for the first time today, was left 1.3secs behind Stoner's early lap.

Honda rider Hayden 0.2secs further back as the top Michelin rider, while West was bumped back to fourth for Kawasaki.

Top rookie was JiR Scot Team's Andrea Dovizioso, two seconds behind Stoner, while Honda Gresini's Shinya Nakano, Rizla Suzuki's Loris Capirossi, LCR Honda's Randy de Puniet, Alice Team's Sylvain Guintoli and Stoner's team-mate Marco Melandri completed the top ten.

Melandri, who fell this morning, was 2.9secs slower than a smiling Stoner, who received a round of applause when he returned to the Ducati pits - before being presented with his new Z4 M Roadster.

Injured riders John Hopkins and Dani Pedrosa chose not to risk further damage and sat out the session.

'Normal' testing will resume at 3.15pm local time and continue until the track closes at 6.00pm. The Jerez test concludes on Monday.

BMW Award:

1. Stoner
2. Rossi
3. Hayden
4. West
5. Dovizioso
6. Nakano
7. Capirossi
8. de Puniet
9. Guintoli
10. Melandri
11. de Angelis
12. Toseland
13. Vermeulen
14. Edwards
15. Jacque
16. Lorenzo
17. Guareschi
18. Canepa
19. Elias