(CNN) -- Defending motorcycle champion Cyril Despres of France won the 13th and penultimate stage of the Dakar Rally on Friday.
Spain's Coma is set to claim overall victory in Buenos Aires on Saturday.
The stage from La Rioja to Cordoba in Argentina was shortened after inclement weather conditions, but KTM rider Despres made light of the heavy rain to win by one minute and 45 seconds from arch-rival Marc Coma of Spain, also riding a KTM.
Coma leads by nearly one and a half hours overall and barring disaster on the final leg into Buenos Aires is guaranteed a second Dakar title to add to his 2006 triumph.
Coma is still cautious about his prospects with over 220 kilometers of special stage riding to come.
"Saturday will be a long stage. In the previous Dakars, we were used to a short final stage around Lac Rose (in Dakar).
"Here, we have 220km of special stage. That's a lot and a lot can happen too," he told the official race Web site www.dakar.com.
David Fretigne, on a Yamaha, was third on Friday at two minutes and 37 seconds and is third overall.
In the cars section, victory on the shortened stage went to Spain's Nani Roma, driving a Mitsubishi.
He finished over seven minutes ahead of Poland's Krzysztof Holowczyc (Nissan) and Frenchman Guerlain Chicherit (BMW).
South African Giniel De Villiers maintained his overall leadership by two minutes and 20 seconds from Mark Miller of the United States.
The Volkswagen pair took command after teammate Carlos Sainz of Spain crashed out in Thursday's 12th stage.
This year's race has been hard-hit by the weather with the 11th stage on Wednesday called off, but organizers look set to return to South America in 2010 after moving from North Africa due to security fears.