Spain's defending champion Carlos Sainz, all but conceded defeat in his bid to retain the Dakar Rally car title after losing nearly 10 minutes on his teammate and main rival, Nasser Al-Attiyah.

Sainz, a two-time world rally champion, had got back into contention by winning on Tuesday but Wednesday was a disaster in a stage won by South African Giniel de Villiers driving like Sainz and Al-Attiyah, a Volkswagen.

Sainz could only finish fifth, conceding 9min, 19sec to Al-Attiyah, who was fourth on the stage, which leaves the Spaniard 12min, 37sec adrift with the race set to finish on Sunday.

"If Nasser doesn't make a mistake, then it is over," said Sainz.

"I lost a lot of time. I didn't have any luck today. We got stuck at the beginning then took the wrong turn two or three times.

"We also had a puncture and I broke the gearbox near the end."

Al-Attiyah, second to Sainz last year and who doesn't enjoy cordial relations with his teammate, said he had enjoyed himself.

"We got lost for seven or eight minutes but then we caught up with Stephane Peterhansel, and we tried to find the right way," said the 40-year-old, who is also a notable shooter and finished fourth in the skeet competition at the 2004 Olympics.

"Then suddenly I saw Giniel de Villier's car and I tried to follow him. From then I said we must stay calm, take it easy and try and find the way. I think it's a big day for us."

Earlier, Sainz's compatriot Marc Coma had tightened his grip on the overall standings in the motorcycling section when he won the stage between Copiapo in Chile and Chilecito.

The KTM motorbike rider ended the 862km run with a near 10-minute cushion over his French teammate, Cyril Despres, who is lying second to Coma, over 18min adrift, in the overall standings.

Coma said while delighted with the victory he was not going to be premature in celebrating overall triumph.

"There are two very hard days left and the last special to think about as well," he said.

"Today it was good right from the start and I simply rode fastest."

Chile's Lopez Contardo took third in the stage at 21min, 43sec, with Dutch competitor Frans Verhoeven half a minute off the pace in fourth.