Rossi and Hayden back in testing mode at Laguna Seca

Valentino Rossi and Nicky Hayden will practically revert back to winter testing mode as both prepare for this weekend’s US Grand Prix at the spectacular Laguna Seca circuit.

The factory Ducati duo are likely to ride the old GP11 Desmosedici in California, while also using practice to carry out a back-to-back comparison with the radically revised GP11.1, which Rossi has been riding since Assen.

Ducati is desperate to try and improve results in the second half of 2011 but the direct comparison will help with development of the new 1000cc GP12.

The GP11.1 features a new swingarm, chassis and rear suspension system that Ducati was developing for its GP12 project.

But the characteristics of the bike are not the same with the 800cc GP11 motor and Rossi and Hayden were split by less than a tenth-of-a-second in last Sunday’s German MotoGP, despite riding two different machines.

Rossi and Hayden held lengthy talks with Ducati management and engineers on Sunday afternoon in the Sachsenring.

And the outcome was both will use one GP11 and one GP11.1 each at Laguna Seca, which hosts round 10 of this year’s MotoGP World Championship on Sunday.

Rossi, who slumped to ninth in Germany, his worst Ducati result, said: “I think that we’ll try to use both versions of the Desmosedici on Friday so that we can compare them and do some work for both the near term and the future, because we want to learn as much as possible.

“We’re aware that it could be difficult because we’ll also have to be preparing for the race, but we think that in order to improve our bike, it’s important to try everything possible.”

Hayden, who won his home race in 2005 and ’06, said: “I think we’ll make the final decision on Thursday as to which bike I’ll ride, but we’ll probably try the GP11.1 at some stage, and I’ll see what I can do to try and come up with a good result.”