MotoGP rookie Marc Marquez continued his unbeaten run at the Circuit of the Americas by dominating the first ever grand prix track session in Austin, Texas.

Quickest during all three days of a private test last month, Marquez moved to the top after seven minutes of FP1 and was over two-seconds clear by the midway point.

Riding in bright and sunny, but cool and slippery conditions, lap times continued to tumble.

Marquez - who claimed a fighting third place on his MotoGP debut in Qatar - remained ahead. However his advantage over Yamaha's reigning world champion and Qatar winner Jorge Lorenzo was cut to just 0.253s by the conclusion of the 45-minutes.

But there is plenty more to come. Marquez's best lap was a 2m 8.756s, compared with a 2m 3.281s on the third and final day of testing.

Dani Pedrosa - Marquez's Repsol Honda team-mate - was over 1.6s behind the reigning Moto2 champion, in third place this morning.

Ducati riders Andrea Dovizioso and Nicky Hayden were not among the 'favoured five' that could afford the private test, and thus performed admirably with fourth and fifth places, albeit two-seconds from Marquez.

Kentuckian Hayden, like home-state heroes Ben Spies and Colin Edwards, had ridden the circuit on a road bike. Dovizioso - the quickest Ducati throughout the Losail weekend - was starting from zero.

Lorenzo's team-mate Valentino Rossi was a surprising low sixth place, given his test attendance. However LCR Honda's Stefan Bradl - the fifth full-time rider with prior COTA MotoGP knowledge - also proved it was no guarantee of FP1 form with ninth.

Although unable to test, the Monster Yamaha Tech 3 and Gresini Honda riders should at least have benefited from gear ratio and other basic set-up data passed on by the factory teams.

Alvaro Bautista (Gresini) and Cal Crutchlow (Tech 3) began the weekend in seventh and eighth places, with Spies (Pramac Ducati) completing a top ten covered by four seconds.

This is the first event where the privateer CRT riders will have a softer specification rear tyre available relative to the manufacturer riders. CRT rear tyre choice is soft and medium, while manufacturer riders have medium and hard compounds.

Quickest CRT this morning was PBM's Yonny Hernandez, in eleventh, despite a technical problem. Claudio Corti (Forward Racing), Bradley Smith (Tech 3), Edwards (Forward) and Aleix Espargaro (Aspar) completed what would be the points positions on Sunday.

Rookie Andrea Iannone (Pramac Ducati) was the slowest of the manufacturer riders in 18th, 6.1s from former Moto2 rival Marquez.

Two American wild-cards are joining the grid this weekend, in the CRT class: Blake Young with Attack Performance and Mike Barnes for GP Tech Suzuki. Both have tested their machines at the track, but were left at the tail of the timesheets in FP1, with Barnes 12.7s slower than Marquez.

A small fire broke out in the Tech 3 pit in the early hours of Thursday, triggering the automatic fire system and drenching the contents of the garage. The sprinkler system in the Factory Yamaha, LCR Honda and Cardion AB team garages was also activated, requiring a major clean-up operation prior to practice.

FP1 was the first daylight grand prix session of the year, round one having been the Losail night race. Second free practice takes place this afternoon.

Friday practice (1):

1. Marc Marquez
2. Jorge Lorenzo
3. Dani Pedrosa
4. Andrea Dovizioso
5. Nicky Hayden
6. Valentino Rossi
7. Alvaro Bautista
8. Cal Crutchlow
9. Stefan Bradl
10. Ben Spies
11. Yonny Hernandez
12. Claudio Corti
13. Bradley Smith
14. Colin Edwards
15. Aleix Espargaro
16. Randy De Puniet
17. Karel Abraham
18. Andrea Iannone
19. Danilo Petrucci
20. Hiroshi Aoyama
21. Bryan Staring
22. Hector Barbera
23. Michael Laverty
24. Lukas Pesek
25. Blake Young
26. Mike Barnes