MotoGP champion Marc Marquez and Repsol Honda team-mate Dani Pedrosa began a private three-day test at Brno on Tuesday.
A heavy rain shower at 11.30am drenched the Czech circuit, leaving the pair to try some wet settings. Marquez, who has won all nine races so far this season, suffered a small crash in turn five after losing the front.
By mid-afternoon it was dry enough to resume the planned testing program, albeit with low grip levels and both riders remained on their current 2014 machines, recording 49 laps each.
Marquez and Pedrosa plan to make their debut on the 2015 RC213V on Wednesday.
"Today went fairly well, in the morning it rained and we were able to test out a few things on a wet track and I had a small crash," said Marquez. "By the afternoon it had already dried out, although the grip levels weren't too good. The important thing is that right at the end we had higher temperatures and a little more rubber on the asphalt, so we could try some initial changes to the setup. Let's hope that conditions are better tomorrow."
Pedrosa, currently second in the world championship, added: "We had a mixed session on this first day. It rained a lot at midday, so we were able to ride in wet conditions. After lunch the asphalt had dried out, but the track was still really dirty and didn't offer us much grip. So unfortunately it wasn't really a day in which we could test too many things. Let's hope that tomorrow we can make better use of our track time to continue working."
No lap times were released by Honda.