Arica - Spain's defending motorbike champion Marc Coma reduced the overall lead of bitter rival Cyril Despres to just 16 seconds after Wednesday's 10th stage of the Dakar Rally.
Neither won the stage - that honour went to Coma's compatriot Joan Barreda Bort - but Coma came in second to make significant headway in his bid to deprive Despres of a fourth Dakar win.
Despres - whose relations with KTM team-mate Coma deteriorated after stewards halved the Frenchman's huge deficit on Monday's stage - came in fourth.
The cars were still out on the route but the whole complexion of the race had been turned on its head with a decision taken off piste.
American Robby Gordon's hopes of winning took a major hit on Wednesday when stewards ruled that he should be thrown out of the event because his Hummer's engine did not conform to race regulations.
A source close to the organisers revealed that the 43-year-old - who is pressing overall leader Stephane Peterhansel hard for the car title - would appeal the decision and was allowed to continue competing in the 10th stage.
The ultimate decision rests with motorsport's governing body, the FIA.
Gordon - whose best finish so far in seven Dakar participations is third in the 2009 edition - won the ninth stage on Tuesday to cut Frenchman Peterhansel's overall lead to 5min 58sec ahead of Sunday's finish in Lima.
It is believed that the stewards noticed the problem with his engine in checking it over after the stage - which had seen his Hummer team-mate and defending champion Nasser Al-Attiyah forced to retire after another technical problem.
The stewards believe that Gordon's modifying of the ventilation system linked to his engine improved its performance level - he denies that his tinkering had an impact on improving its speed and is basing his appeal on that.
Peterhansel is bidding for a 10th win in the testing race, six in the motorbikes and thrice in the cars.