One day after wondering if he could even ride, Casey Stoner sprinted to the top time on the hot and sultry second of three days of MotoGP testing at the Sepang Circuit.

Reigning World champion Stoner was rendered immobile when a nearly decade-old back injury flared up as he was preparing for the start of the test on Tuesday morning.

The injury, suffered in the 125cc GP in the 2003 Dutch TT, put him out of action and onto the physiotherapist’s table after only a few exploratory laps. But when he woke up on Wednesday morning, and with the help of some over-the-counter medication he was ready to ride.

The 26-year-old Australian spent the day comparing the new RC213V chassis to the one he had tested at the end of 2011 in Valencia.

The diligence paid off, with the team finding a direction for the third and final day of the test, while giving Stoner a machine on which he could set both the day’s best time and one of his personal best.

“It was great to be able to ride today and everything went pretty well, although I would have liked to have done a few more laps,” Stoner said. “We spent most of the day on the new chassis comparing it back to back with the one we had in Valencia and we found a good direction and where we want to go.

“As usual, it would be great to take some elements from one chassis and some from the other, but at least we found the direction we are happy to follow. We used the hard front tyre this afternoon, but found we had more chattering with it so we have to work on this.

“There is still room for improvement. We didn’t get a chance to use the new spec tyres that Bridgestone have brought here. We’ll try them out tomorrow and go from there.”

Stoner was the only one to lap the 5.548Km track under the two minute one second target, with a best of 2:00.895s.