Sepang: MotoGP champion Casey Stoner had to sit out the start of pre-season testing on Tuesday after the Repsol Honda rider pulled his back doing warm-up exercises at Malaysia`s Sepang Circuit.
The Australian, who will be chasing his third title in the top category this year, received treatment and was hopeful of riding on Wednesday.
"I was stretching this morning for a good 20 minutes preparing to go out on track for the first time and then all of a sudden my back just locked up on me," he said in a team statement.
"I couldn`t move or do anything. I had to call someone to come and help me move into a position that was less painful."
"I had some more physio after lunch but it still wasn`t easing up, I felt I could have gone out on the bike in the afternoon but we all agreed it would probably make it worse for tomorrow," said the 26-year-old.
The test ends on Thursday and Stoner was keen to get out and try parts for the new 1,000cc machine that has replaced last season`s 800cc bike.
"I think tomorrow the track conditions will be better and as long as my back improves overnight we should get back on schedule with our testing tomorrow," he said.
Morning rain limited track time on Tuesday with Yamaha`s former champion Jorge Lorenzo of Spain setting the pace, 0.346 seconds faster than compatriot and Stoner`s team mate Dani Pedrosa.
Tuesday`s test was the first time MotoGP had returned to Sepang since 24-year-old Italian Honda Gresini rider Marco Simoncelli was killed in a crash at the grand prix in October.
Honda riders and officials laid flowers at the scene on Sunday.