By Peter McLaren

Valentino Rossi may be the only Yamaha/Bridgestone race rider in this year's MotoGP World Championship, but that doesn't mean he is the only M1 rider using the Japanese rubber.

The Yamaha MotoGP Test Team - as present alongside Fiat Yamaha at this week's Sepang test - also runs Bridgestone tyres, while further development work between Yamaha and Bridgestone takes place in Japan.

"Yes, for sure it is better [to have the test team on Bridgestones] and the test team also works a lot in Japan," said Rossi. "For the Yamaha test riders and test teams it is also a lot easier to work with Bridgestone than to work with Michelin, because before the tyres always had to arrive from France."

Nevertheless, while the Yamaha test team can run-up almost unlimited track mileage, its riders cannot come close to replicating the performance demands made by Rossi.

"The work of the test team is not very important [in that sense]," said the Italian. "They go more slowly. I don't think they can make a lot of difference."

Rossi was fastest of all on day one of the third and final Sepang winter test.

Fiat Yamaha team-mate Jorge Lorenzo, plus Yamaha Tech 3 riders Colin Edwards and James Toseland, use Michelin tyres, as 'worn' by Rossi from 2000-2007.