Sam Sunderland has retired from the lead of the Dakar Rally and been taken away by helicopter with a back injury on stage four in Peru.
Sunderland, 28, was the first Briton to win the event in any class when he took the motorbike title last year.
He led going into a 330km special stage at San Juan de Marcona but failed to reach the fourth checkpoint on Tuesday.
Sunderland carried on for 5km after the initial injury before experiencing "a lack of feeling in his legs".
"It seems that when he was searching for one of the WPC [way point controls] he jumped into a big hole and suffered a big compression," KTM team manager Alex Doringer told MCN.
"He felt a sharp pain in his back immediately, but carried on for another 5km before stopping again due to the pain and a lack of feeling in his legs.
"He said that the feeling in his legs has returned."
Sunderland has been treated by team medics and will now be flown to Peruvian capital Lima for more tests.
Adrian van Beveren of France won the stage to take the overall lead.
The race - formerly known as the Paris-Dakar - moved to South America in 2009 and this year takes place in Peru, Bolivia and Argentina, ending in Cordoba on 20 January.