Valentino Rossi made his much anticipated debut on board the Ducati Desmosedici on Tuesday. The Italian turned laps at the Valencia circuit as part of a two-day MotoGP test along with 16 other riders (view the results in our 2010 MotoGP Valencia Day 1 Test Results). The 31-year-old hopped aboard the Ducati wearing plain black leathers, contrasted strongly by his neon Number 46 written across his back.Rossi?s first trip lasted just eight laps so he could get an initial feel for the bike. The team first utlilized the big bang engine for much of the first day, and worked on additional items such as geometry. Rossi then set out on the screamer version, making one final pass before calling it a day. Overall, the Italian set a best time of 1?35.134, and finished the first day of testing in 10th directly behind his Ducati teammate, Nicky Hayden. For Ducati the stated goal of this test is to determine whether to go with a screamer or big bang engine for the upcoming season.