Yamaha duo not getting carried away

The pair edged out Ducati's Casey Stoner to take first and second at the end of the hour-long session at a hot Mugello.

"This is a great start but it's too soon to speak about the race or jump to conclusions; we've only had one practice," said Lorenzo, who leads the championship after his Le Mans win.

"It's true however that I didn't have any problems today and I felt very happy for the whole session. Each time we come to a new track we don't know exactly what to expect because we're still learning the new Bridgestone tyres but at the moment we seem to be fast each time and I feel very comfortable in this period; this is positive."

Lorenzo's team manager Daniele Romagnoli said there was even more to come from the Spaniard.

"We've got the weekend going in the best way, especially because Jorge is already under the lap record which shows how comfortable he is," he said.

"We're very happy with the bike but we have already found some areas that we can improve so this will be our task for tomorrow. Let's hope we can keep going in the same way because we know that everyone else will improve as well."

Rossi had been quickest for much of the session, and has won the last seven races at Mugello, but was pipped by his team-mate near the end.

"We did quite well today and it looks like we're in good shape," said the reigning champion. "It is only Friday so there's a long way to go yet, but it's looking like it could be a great battle on the track because the first few riders are very close.

"We have a few small things to work on still with the setting because I can't ride exactly how I want to yet, but we already have a good rhythm and we have important data to help us improve further.

"This is a great track for me and it doesn't matter if Mugello comes after a bad race or a good one, it's something apart from the 'normal' championship and I always feel great motivation."