Stoner sickness threatens his weekend

While the world champion's Ducati was just over a tenth faster than rival Valentino Rossi in the second session on Friday, the Australian admitted that he felt weak and could not manage more than short stints on the saddle throughout the day.

Stoner was so ill that he was forced to cancel his regular post-practice press session in the afternoon.

"I've not been feeling well for a few days and I felt very weak today - I even felt sapped of energy just putting my gloves on," said Stoner. "I can deal with a bit of tiredness but this afternoon I could only ride a handful of laps before I started to feel cramps in my stomach.

"That doesn't help my crew because I've not been able to put many consecutive laps together and this morning wasn't too good for us, we struggled to find the right set-up for this new surface."

Despite Bridgestone's apparent superiority at Brno, Stoner also raised concerns that the resurfaced track had proven tough on the rubber and required a hard compound.

"To look at you'd think it would be smooth on the tyres but it's actually quite aggressive, particularly on the front," said Stoner. "This afternoon we went with a harder compound front tyre - similar to what we used at Laguna and Sachsenring, which is about the hardest we've got - and we had to work on the geometry to get the most effective load on the front tyre.

"The guys improved the bike every time I came in so it was frustrating not to be able to put it all together with a long run. We still have a lot of work to do so hopefully I'll feel better tomorrow and the weather holds out for us."

Stoner's teammate Marco Melandri, who has already confirmed his exit from Ducati at the end of the season and is enduring the worst year of his MotoGP career, was boosted by making the top ten in the morning session.

Unfortunately, the Italian lost ground in the afternoon and ended the day a distant 15th out of 17 runners.

"We started out well this morning and did some decent lap times but in the afternoon we didn't manage to make progress with the set-up and as the other riders improved we lost more and more ground," said Melandri. "The bike is moving around a lot, especially on the rear, so that's an area we have to work on tomorrow - weather permitting.

"The new surface has improved the track overall although there are still a few bumps here and there."