Casey Stoner's hopes of retaining his MotoGP World Championship crown have suffered a set-back after a mid-race off consigned him to a lowly eighth place finish during the Italian Grand Prix at Mugello.

A week after his crash just two corners from the end of the German Grand Prix, the Australian endured an unusually anonymous weekend on Italian soil as he struggled with the set-up of his Repsol Honda.

The only rider to opt for the 'special' harder Bridgestone rear tyre, Stoner ran towards the back of the chasing pack during the opening stages, but an error on lap ten would see him take a lengthy trip off the circuit at the Correntio bend, dropping him back to a distant tenth position.

Though he fought his way back up to eighth position, administering a robust pass on Alvaro Bautista en route, Stoner eventually crossed the line a frustrated eighth.

"It's definitely not the way we planned it, we thought today we could be fighting for the podium and maybe have the pace to stay with Dani, Jorge has ridden fantastically all weekend and hasn't really put a foot wrong but I think a third position would have been good today. However, we just couldn't get the bike working.

"During our last attempts in warm up we couldn't get anything to work, we weren't very happy with the bike today and I just didn't feel comfortable. I made a mistake in the race, I had a bit of a shake exiting turn 11 and when I arrived at turn 12 I had no brakes

"I was squeezing them as hard as I could and thought I had enough brake power to stop before the edge of the track but I had too much momentum and had to ride through the gravel trap which wasted a lot of time."

Reflecting on his clash with Bautista, which was prompted when Stoner's aggressive attempt to pass at turn two saw him run wide and make contact with the Spaniard, the two-time champion apologised for the incident.

"I'm sorry for the incident with Alvaro, I went to make the pass into turn 2 and he started to close my front off and I couldn't do anything. It's a disappointing end to a difficult weekend that I thought I might be able to salvage something from but unfortunately not."

Scoring just eight points at the Sachsenring and Mugello, Stoner finds himself 37 points behind Jorge Lorenzo in the overall standings with nine races remaining.