AUSTRALIAN STAR CASEY STONER is set to undergo further medical testing after again struggling with illness at the Laguna Seca round of the MotoGP championship.
The 2007 World Champion has struggled with a mystery ailment since the Catalunya Grand Prix, fading in the last three events with an onset of fatigue.
While the illness wasn?t the sole contributor to his performance in the US - the Ducati rider struggled with a wrist injury following a fall in qualifying - team boss Livio Suppo said the outfit is keen to identify the problem plaguing Stoner.
?He says he feels a lot better stomach-wise, as the sickness felt at Barcelona and Assen went a lot better,? he said.
?Despite that, especially in the last laps, he lacked concentration, and he told me he practically had to lean on the fuel tank under braking. His left arm felt very uncomfortable, so he wasn't at his best.
?Tomorrow we'll do a series of medical tests and we'll take advantage of being here to do them immediately instead of waiting to be back in Europe.
?Together with our doctors in Italy and with Clinica Mobile we've gathered all the things that need to be verified, and I think we'll understand well how to intervene.?
Stoner bounced back from his qualifying mishap to remain in the hunt for the early part of the race, at one stage sitting in second place as he fought to halt the advances of Yamaha teammates Valentino Rossi and Jorge Lorenzo.
However, as the race entered its closing stages, Stoner quickly fell off the pace, drifting away from a podium position to eventually finish 10 seconds behind Lorenzo.
Despite the late-race lapse in form, Stoner was pleased with his performance, which sees him remain in contact with the main championship contenders.
"Today I didn't feel as bad at the end of the race as I have done in the last two but I'm still not right. I found it really difficult to keep my concentration over the last few laps and I was in a bit of a daze by the end,? Stoner said.
"My left arm was feeling really tired by the end because of the fact there are so many left-handers here and my left wrist still doesn't have the full range of movement after my operation in the winter. I'm really disappointed because without all of these problems we could have done so much better.?
Spaniard Dani Pedrosa won the event to break Honda?s winless streak, with Rossi and Lorenzo rounding off the podium, while Stoner?s teammate Nicky Hayden finished fifth in a season best performance.