Repsol Honda's Marc Marquez put his data and track knowledge to good use in the first MotoGP free practice session at Austin, topping the timesheets but he was run close by reigning champion Jorge Lorenzo with his last lap.
The Spanish wunderkind started fast and had a lead of more than two seconds at the halfway point until Lorenzo and his Yamaha found their mojo and he started to cut the gap until he got it down to a quarter of a second with his final effort.
Marquez's quickest, on his ninth lap of 16, was a 2'08.756 compared to Lorenzo's 2'09.009 but third-placed man Dani Pedrosa is a country mile behind with a 2'10.356 - some 1.6s slower than his HRC team-mate.
A flurry of fast last laps saw Ducati's Nicky Hayden briefly occupy fourth spot with a 2'10.801 but he was demoted by the other works Desmosedici of Andrea Dovizioso on his final circulation, the Italian going round in 2'10.665.
Valentino Rossi eventually bagged seventh place after running in the top three early on but The Doctor is some two seconds off the pace of Marquez. Alvaro Bautista placed eighth, one ahead of Cal Crutchlow on the Monster Yamaha, who is 2.5s slower than Marquez.
Stefan Bradl and Ben Spies round out the top ten while while Yonny Hernandez, on the PBM Aprilia, was quickest CRT before his engine let go. Claudio Corti put the NGM Forward bike in second, ahead of Bradley Smith, while Colin Edwards finished the CRT top three.
Britain's Michael Laverty, on the second but differently-chassied PBM bike, was 23rd out of 26 runners.
