Valentino Rossi began his third race weekend back from a broken leg, at the Brno event he had originally targeted for his MotoGP comeback, with third in Friday practice.
The world champion was fastest several times during the session, most latterly from the 29th to 36th minute, but was then out-paced by Fiat Yamaha team-mate Jorge Lorenzo and Repsol Honda's Dani Pedrosa.
Rain in the final fifteen minutes brought an early end to the session, but Rossi was pleased with how his fitness has improved in the two-weekend break since Laguna Seca.
"I'm happy, this was a good practice and I feel good on the bike," said Rossi who was 0.606sec slower than Lorenzo but only 0.065sec off Pedrosa. "After some laps I started to feel some pain in the shoulder and the leg but in general I am okay and my condition has improved a lot from the last race.
"We've done a good job on the setting and I was [among the] fastest throughout most of the session. It was a pity the rain came because we couldn't make the final step, but hopefully we can improve again tomorrow.
"Even though I still have some pain I am quite a lot stronger, especially with the shoulder, so I don't have such a big problem in braking," revealed Rossi, who won at Brno last season.
"It seems we're in good shape," stated team manager Davide Brivio. "Tomorrow we will continue to fine-tune the setting and hopefully make another step with the lap times."
Rossi hasn't won a race since round one in Qatar, but took his first podium since his leg injury with third last time out at Laguna Seca.