Nicky Hayden made the perfect start to his final weekend for Honda by leading both of Friday's free practice sessions for the season-ending grand prix at Valencia - on a day when world champions Valentino Rossi and Casey Stoner both fell in the wet conditions.

Having been 0.775sec clear of nearest rival Stoner in the morning, Hayden was soon back on top of the afternoon hour, a session which saw the rain steadily easing and produced the fastest lap times of the day as a result.

The Kentuckian found himself pushed down to fourth by the halfway stage, but rebounded by nudging Valentino Rossi from the top with 29 minutes to go. Dani Pedrosa made it a Repsol Honda one-two shortly after and the factory RCVs held formation right to the finish.

Michelin-shod Hayden, without a win since his title winning 2006 season, finished the day just 0.087sec in front of double 2008 winner Pedrosa (using Bridgestone tyres), but Hayden had been 0.4sec inside his best lap time with five minutes to go when a small mistake ruined the lap.

Meanwhile, Rossi - who lost the 2006 world title by falling at Valencia, then saw second in the 2007 world championship slip away when his M1 broke down at the same venue last season - suffered further Valencia drama on Friday, finishing an uncharacteristic 13th in morning practice and then falling from his Fiat Yamaha in the afternoon session.

The recently crowned six time MotoGP champion, chasing his tenth win of the season on Sunday, was holding third when the rear of his machine suddenly spun-out on entry to the off-camber final corner, with 18 minutes remaining.

Rossi slid away unharmed and, after a failed attempt to bump-start his machine, returned to the pits for his spare bike. The #46 returned to the track in the closing stages but couldn't prevent rookie team-mate Jorge Lorenzo - riding with a special Lorenzo's Land livery - nudging him down to fourth during the final minute.

Stoner, who escaped injury during a fast highside this morning, led the afternoon session from the 15th to the 28th minute, when Rossi briefly took control, before setting into fourth - a position he yielded to Lorenzo in the final minutes.

Future Repsol Honda rider Andrea Dovizioso, who took his first MotoGP podium last weekend in Malaysia, was sixth fastest for JiR Team Scot, with Honda LCR's Randy de Puniet 0.283sec slower and the first rider outside one second of Hayden.

Sylvain Guintoli should have been celebrating an impressive eighth on the opening day of his final weekend before moving to BSB, but the Alice rider fell awkwardly with four minutes to go and had to be carried out of the gravel by marshals after sustaining a leg injury.

The Frenchman's accident concluded a dour day for Alice, an angry Toni Elias having been unceremoniously dumped from his Ducati after 22 minutes and - although unharmed - appeared not to have returned thereafter, leaving him 18th and last.

The leading Suzuki rider was Chris Vermeulen in a lower than expected eleventh, while John Hopkins got the better of rain master team-mate Anthony West to lead the Kawasaki challenge in 14th.

Friday practice (2):

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