IndyCar organisers have announced Will Power suffered 'no definitive evidence of a recent concussion' after his Friday practice shunt at the Firestone Grand Prix of St Petersburg, passing all medical assessments.

The 2014 IndyCar champion dropped out of the race after suffering with an illness despite putting his Team Penske machine on pole during Saturday's qualifying and was subsequently replaced by Oriol Servia.

It was reported the 35-year-old was forced to miss the race after suffering concussion during a crash on Friday which he failed to recover from but IndyCar organisers have since released this statement:

"INDYCAR announced today that results of an extensive evaluation at the University of Miami Concussion Program revealed no definitive evidence of a recent concussion for Verizon Team Penske driver Will Power," the statement read. "The 2014 Verizon IndyCar Series champion passed the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) test and a MRI/DVI study was normal in all parameters. Power was evaluated by a team of physicians specializing in concussions.

"Power has been cleared to return to Verizon IndyCar Series competition after sitting out race day on-track competition for the Firestone Grand Prix of St. Petersburg on March 13."

Dr Terry Trammell, safety consultant to IndyCar, believes his symptoms may have been due to an inner-ear infection and ruled out concussion.

"There is no evidence that he sustained a concussion in the crash on Friday, which is consistent with his ear accelerometer data and the mandatory screening evaluation conducted after his crash," Trammell said. "Given the nature of his inner-ear infection, it would have been extremely difficult for Will to pass the SCAT, which is what ultimately led to the concussion diagnosis.

"At the University of Miami they conducted a week's worth of testing in one day and Will was seen by multiple physicians. The doctors concluded definitively that Will had not sustained recent head trauma."