Gronholm is 19 points behind Loeb at the top of the standings

The pair won all six stages between them on Friday to leave the rest of the field trailing behind.

Gronholm won the first three stages in his Ford Focus before Loeb, in a Citroen, hit back to win the next two.

Loeb was narrowly beaten to the fastest time of the final stage by Gronholm, who holds a 35.4-second overnight lead.

Gronholm's Finnish compatriot Mikko Hirvonen is more than a minute adrift in third, with Norwegian Henning Solberg, elder brother of Petter, in fourth.

Loeb, the reigning champion, is chasing his fifth win this season and is just two victories away from Carlos Sainz's all-time record of 26 rally wins.

Petter Solberg, a former world champion, was in contention until he suffered a puncture in his Subaru on stage five.

Citroen youngster Dani Sordo is running a promising fifth, only just ahead of Gianluigi Galli's Peugeot.

Subaru's Chris Atkinson complained of visibility problems in the dust on his way to seventh at the close of day one, while Xavier Pons' Citroen rounds out the top eight.

English rookie Matthew Wilson suffered a nightmare start after his history-making feat in Argentina last time out.

The Stobart Ford driver became the youngest world champion points scorer in South America but was given a one-minute penalty for an engine change before Friday's action began.

When he finally got under way, he hit a rock, damaging his suspension, then needed to change a part on his engine.

He finished the day 47 minutes away from the points.