Casey Stoner unsure about arm pump progress as rain confuses Jerez MotoGP practice

Stoner was leading in Qatar when he developed an arm pump issue that allowed Yamaha's Jorge Lorenzo and his Honda team-mate Dani Pedroza through to claim first and second.

The Honda rider has been treated since the Losail race using similar methods to those used in 2010 when he had the same issue at Silverstone.

"At the moment the arm feels OK, but it's difficult to know when the conditions are like this and you are not stressing it like in the dry," Stoner said.

The Australian finished fourth in second practice, as team-mate Pedrosa set the pace, and said he struggled to understand the bike in the fast-changing conditions.

"We came back in to try and change the bike and give it more rear grip but by the time we went back out it was already starting to dry off a little and we couldn't get a good understanding of the bike," said Stoner.

Pedrosa said his bike felt good and is hoping for more consistent weather for qualifying.

"The first feeling on the bike was good for me, the bike felt good and I am riding well but I hope for better weather tomorrow, full dry or full wet. Let's keep focused and do a good job."