Casey Stoner returns to the scene of his bitter 2008 Laguna Seca defeat this weekend much closer to Valentino Rossi and the MotoGP World Championship lead than after seven rounds of last season, but with concerns over his physical condition.

Last year's US Grand Prix provided the best victory battle of the 800cc era - until the Valentino Rossi/Jorge Lorenzo spectacle at this year's Catalan Grand Prix - with Rossi smothering Stoner's performance advantage with a series of daring passes.

The pair fought elbow to elbow around the rollercoaster circuit but the fans were denied a grandstand finale when Stoner ran off track and crashed, returning to claim second place.

The Ducati star was initially very unhappy at some of the passes made by the Rossi, but later calmed down, although his title chances disappeared after he fell from the lead at the next two rounds.

Unsurprisingly, Stoner didn't want to dwell on last year's US GP, and has more pressing concerns regarding his physical fitness, having required medical treatment for exhaustion after the last two races.

“We have had some setbacks over the past couple of races that have prevented us from showing our full potential,” he said. “We have done a lot of work on the bike and found a great set-up for the race on both occasions but I have not been in good shape when it was the moment to take advantage of that work.

“We have come straight to America from Assen and there hasn't been much time to recover, although I do feel better already,” he claimed. “What we learned from last weekend is not to underestimate the symptoms.

“I have always liked Laguna, with its natural elevation changes, I love racing in America and the Ducati has always gone well here. We have the potential to challenge for a good result again but we'll wait until we get out on track and see how things shape up,” the 2007 world champion concluded.

Despite the fatigue, Stoner has been able to claim two third places at the last two rounds and is just nine points from world championship leader Rossi, and only five behind the Italian's Fiat Yamaha team-mate Jorge Lorenzo, after seven races.

After the first seven races of last season, Stoner sat fourth in the championship, a massive 50 points behind Rossi. Laguna Seca was round eleven of the 2008 season.