Jorge Lorenzo struck the first blow at the Italian round of the FIM MotoGP World Championship as he was quickest in the opening practice session at Mugello.
The Fiat Yamaha rider, who leads the championship points standings from team-mate Valentino Rossi, made the most of the fine conditions to set the best time.
Having won two of the four races this season, the last of which was run in drying conditions at Le Mans in France, Lorenzo made the most of the sunshine in Italy for his team's home round.
Lorenzo headed home the next three riders in the standings as Rossi, Casey Stoner (Ducati Marlboro) and Dani Pedrosa (Repsol Honda) also occupied the second to fourth four spots in practice.
Lorenzo was the only rider to set a time under one minute and 50 seconds as he topped the session with a best of 1:49.870.
Rossi, who has won for the last seven years at Mugello, was two tenths of a second slower than his team-mate.
In front of Ducati's fanatical fans, Stoner was third quickest but was 0.274 seconds behind the pace set by Lorenzo.
Pedrosa's time of 1:50.808 also saw him set a best top speed ever recorded in MotoGP of 349.3kmh, beating the 343.7kmh set by Makoto Tamada in China in 2006.
Rossi and Pramac Ducati riders Mika Kallio and Niccolo Canepa also beat the previous Mugello top speed of 343kmh set by Alex Barros.
Fifth best time today was set by Colin Edwards (Monster Yamaha Tech 3) with Alex de Angelis (San Carlo Honda Gresini) in sixth.
Loris Capirossi was seventh quickest at his home race for Rizla Suzuki and Randy de Puniet (LCR Honda) was the eighth best.
Italians Andrea Dovizioso (Repsol Honda) and Marco Melandri (Hayate Racing) rounded out the top 10.
