MotoGP rookie Marc Marquez set the fastest lap time on day one of the private Honda/Yamaha test at the new Circuit of the Americas in Austin, Texas.
Riding his Repsol Honda RC213V for the eleventh time, the new venue put Marquez on a more even footing relative to his experienced MotoGP rivals.
As on Austin's F1 race debut, late last year, the circuit was initially very slippery, with lap times in the 2m 12s range. However as the track became cleaner and temperatures increased, times steadily dropped.
Moto2 champion Marquez eventually ruled the timesheet with a 2m 4.619s, on lap 54 of 55. That put the young Spaniard 0.428s clear of team-mate and next quickest rider Dani Pedrosa. Marquez and Pedrosa have tested together for a total of eight days, but Tuesday marked the first time that 20-year-old Marquez has out-paced last year's title runner-up.
Yamaha's world champion Jorge Lorenzo was 0.672s behind Marquez, with LCR Honda's Stefan Bradl (1.434s) and Lorenzo's team-mate Valentino Rossi (+1.888s) in fourth and fifth.
“The first day in Austin went pretty well,” said Marquez. “It is a fun circuit, because there's not a single bump on the track. There was no grip at the start and we were sliding around a lot, but gradually the lines were cleaned up and we could tackle it better.
“In the first part of the track, where the flowing chicanes are all linked up, it is a very tricky section. It is a physically demanding part of the circuit where you have to use a lot of strength to change direction quickly. It is definitely a key point of the track.
“There are three right-handers later on, all linked together, making it hard to find the ideal line. We are finding our way steadily though. Today was all about learning those lines, rather than trying out too many things with the bike.
“Tomorrow we will start to adapt the gearing and the electronics, as we have a lot of work ahead of us."
Marquez has finished seventh (Valencia), fourth (Sepang I) and third (Sepang II) in the official MotoGP tests he has taken part in. Marquez also rode at a private Sepang test last November.
The three-day unofficial Austin test, also attended by the privateer Attack and GPTech CRT wild-cards, will resume at 10am on Wednesday morning.
Austin is joining fellow US circuits Laguna Seca and Indianapolis on the MotoGP calendar. It will host its first two-wheel grand prix in April.
The final official MotoGP test will be held at Jerez later this month.