Factory Ducati rider Casey Stoner ended opening practice for Sunday’s American MotoGP race with the fastest time after an intense early weekend battle with Jorge Lorenzo.
Lorenzo first moved to the top of the leaderboard in search of his first win in California with just over a quarter of the session elapsed.
A 1.22.866 knocked Fiat Yamaha rival Valentino Rossi off top spot after the Italian had made an impressively fast start to the hour-long session that was run in sunny but cool conditions.
A series of blistering laps extended the Spaniard’s advantage to almost half-a-second before Aussie Stoner mounted his decisive attack shortly before the halfway point.
A lap of 1.22.640 put the 24-year-old within striking distance of Lorenzo’s factory Yamaha YZR-M1, Stoner lapping just 0.110s behind the runaway world championship leader.
Stoner then logged a lap of 1.22.201 to surge over 0.3s clear of Lorenzo, who will start Sunday’s 32-lap American MotoGP encounter with a commanding 47-point lead over fellow Spaniard Dani Pedrosa.
Lorenzo, who has yet to finish outside the top two in the opening eight races of the season, got to within 0.007s of the 2007 world champion before a lap of 1.22.133 with 18 minutes remaining put Stoner just 0.075s clear.
Stoner made sure he took the spoils with a brilliant late lap of 1.21.699. That put him over 0.5s clear of Lorenzo and the 23-year-old was only able to reduce the deficit to 0.233s.
Lorenzo ended with a best time of 1.21.932 to finish 0.293s clear of Italian Andrea Dovizioso.
Repsol Honda team-mate Dani Pedrosa, winner of last weekend’s Sachsenring race in Germany, was fourth fastest with a best of 1.22.559. That left him 0.860s behind Stoner and 0.334s away from Dovizioso.
Home favourite Ben Spies, who has won three American superbike races at Laguna Seca, occupied fifth place with a best lap of 1.22.640 that was only 0.081s behind Pedrosa.
The 26-year-old Texan was the last ride to lap within a second of Stoner with reigning world champion Rossi in a respectable sixth spot.
The Italian, starting only his second Grand Prix since breaking his right leg in Mugello back in early June, was just 0.020s behind Spies with two-time American MotoGP winner Nicky Hayden in seventh.
Colin Edwards was eighth fastest as he benefited from an engine upgrade from Yamaha that was also used by Monster Yamaha Tech 3 team-mate Spies.
Edwards logged a best time of 1.22.971 to finish 0.069s behind Hayden.
Marco Simoncelli recovered from an early crash on only his third lap at turn three to post the 12th best time. The Italian clocked a best time of 1.24.002 with top rookie award going to Aleix Espargaro in tenth.
Roger Lee Hayden deputising for the injured Randy de Puniet, took the LCR Honda to a best lap of 1.25.432 to finish in 17th place.
He was 3.733s behind Stoner’s impressive pace but just 0.401s behind Alvaro Bautista’s factory Suzuki GSV-R.