Honda rider Dani Pedrosa says a lack of grip from Michelin's rear tyres made his team's second day of pre-season MotoGP testing at Sepang very hard.
All riders were forced to use the harder tyre compound following Loris Baz's dramatic accident at high speed, which happened while riding with the softer of the compounds.
Michelin decided to withdraw the tyres as it investigated the cause of the problem.
Pedrosa admitted having to use the hard tyre meant Honda was unable to make any progress during the day.
"There was almost no grip on the rear for us, so it was very difficult to manage and to get some improvements on the bike," Pedrosa told reporters after the session.
"We tried some different eight distributions today and checking which one is better, but we couldn't come up with a good idea.
"We have to wait until tomorrow to see which tyres we can use.
"This will be important, because today we were using the hard and with the hard is quite difficult to have a good feeling because the grip is not so high."
The Spanish rider finished down in 12th position in a session during which he was one of several riders to crash at Turn 5.
Pedrosa said he was not sure about the cause of his accident.
"I wasn't really going fast because I had just come out of the pits," he said. "I guess the tyre was cold or something like that."