Rossi, Lorenzo debut 2015 Yamaha

Jorge Lorenzo and Valentino Rossi made their debut on the 2015 YZR-M1 during Monday's MotoGP test at Brno.

Back at a circuit where they had finished second (Lorenzo) and third (Rossi) during Sunday's race, Lorenzo led for much of the afternoon, eventually finishing second to Honda's world champion Marc Marquez by 0.155s.

Both Movistar riders tried the full 2015 prototype and also a 2015 engine in the 2014 frame.

"We tried a few things for the bike for next year and it's quite good in some aspects, negative in others but in general better," said Lorenzo, who rode for 52 laps. "We also tested some factors for this year. The chassis for next year seems a little more stable which is good."

Riding 18 years to the day since his very first grand prix victory, at the same circuit in the 125cc class, Rossi finished fifth on the timesheets. The Italian was 1.035s behind Marquez after his 63 laps.

"The first prototype of the new engine is a small step but it is a little bit better. We also tried the prototype of the new bike. We improved some things, brake and entry is not so bad but in acceleration my feeling is that we lose a little bit. So we have something good and something bad," he explained.

"We have to do some more work but it was important to test today. We also tried some small details for the next races but not so important for the rest of the season. Now we have to take the data from myself and Jorge who was very fast in the morning when the conditions were a bit better."

Team director Massimo Meregalli added: "Today was a very important test as we were able to evaluate the prototype 2015 machine for the first time. It's been a very positive day overall, we have managed to get a lot of useful data from both Jorge and Vale which our engineers will now take back to make the next steps with.

"The team will now take a short rest and after two very intense back to back races be ready to challenge again at Silverstone in two weeks' time."