MotoGP title leader and Brno winner Jorge Lorenzo was once again on top of the timesheets during Monday's test session in the Czech Republic, when he tried new developments for this year and next.

The test day was only the second since the start of the 2010 racing season, and is the last until competition ends at Valencia in November.

Lorenzo finished the test over half a second quicker than nearest rival Casey Stoner (Ducati), although afternoon rain - which brought an early end to the test - meant he didn't get to complete his full schedule.

The Fiat Yamaha rider, now 77 points clear of Dani Pedrosa in the championship, tried a new engine upgrade and suspension setting fro his present race bike, and joined soon-to-be-announced 2011 team-mate Ben Spies in riding Yamaha's 2011 prototype YZR-M1.

"This was an important and interesting test for us, both for the rest of the season and looking towards next year. We had a lot to do but unfortunately the rain forced us to stop early," said Lorenzo.

"As well as the 'new' prototype machine for next year we also tried an engine upgrade and a new Ohlins suspension, but it's too early to know if they will be better for our M1, which is already very competitive.

"We got quite a lot of information though so hopefully it will help the engineers to improve things even more," concluded Lorenzo, who will be chasing his eighth win of the season at Indianapolis later this month.

Lorenzo's team-mate Valentino Rossi, now confirmed as riding for Ducati next season, was fourth fastest (+0.860sec).