2010 MotoGP world champion Jorge Lorenzo, who has never won at Valencia in any grand prix class, knocked Casey Stoner from the top of the Friday practice timesheets on his very last lap of the afternoon session for the season finale.
Lorenzo took his Fiat Yamaha to a lap of 1min 32.690sec to pull 0.314sec ahead of Stoner's Ducati, which had been fastest in morning practice. Stoner lapped slightly slower than he had in the first session.
Two satellite riders impressed on day one with Monster Yamaha Tech 3's Colin Edwards claiming third, 0.776sec from Lorenzo, and rookie Marco Simoncelli just 0.002sec behind the Texan for San Carlo Honda Gresini.
Repsol Honda's Andrea Dovizioso and Edwards' team-mate Ben Spies, riding through the pain of an ankle injury, were fifth and sixth.
Outgoing seven time MotoGP champion Valentino Rossi had been fifth in morning practice, but managed just ninth this afternoon, almost one-second behind team-mate Lorenzo.
Rossi is riding in his final event as a Yamaha rider, before switching to Ducati for 2011. Stoner is moving from Ducati to Honda.
Randy de Puniet (LCR Honda) and Marco Melandri (Gresini Honda) separated Spies and Rossi, who was the slowest M1 rider.
Stoner's Ducati team-mate Nicky Hayden, level on points with Spies for sixth in the world championship, was only tenth quickest at the track where he won the 2006 world championship.
Rookie Hector Barbera was eleventh for Aspar Ducati, with the injured Dani Pedrosa twelfth for Repsol Honda at what has traditionally been one of his strongest events.
Carlos Checa, who retired with arm-pump at half-race distance on his MotoGP return last weekend at Estoril, was 17th and last - directly behind the two Rizla Suzukis.
Friday practice (2):
7. de Puniet