Toyota's Kalle Rovanpera was heading for victory in Greece's Acropolis Rally after stretching his lead to half a minute on Saturday.
The Finn won four of the day's six stages to go from 3.7 seconds clear of Hyundai's Ott Tanak overnight to 30.8 ahead with three stages remaining.
World championship leader Sebastien Ogier, also in a Toyota, was third and just 9.4 seconds behind the second-placed Estonian after winning the day's penultimate stage.
"If we can finish on the podium tomorrow it will be another big step to the title," said the French seven-times world champion.
"Kalle was extremely fast this morning and took a big lead, so well done to him for a very strong day. The afternoon loop was better for me. It’s always important to keep a bit of pressure on, we are not that far from second place."
Ogier started the rally 38 points clear of Welsh team mate Elfyn Evans with three rounds remaining after Greece.
Evans lost five minutes with a gearshift issue on Friday but came back strongly on Saturday and went from 16th to seventh place.
"I don’t think there’s a chance to climb up any further providing those ahead don’t have any trouble now, but we want to try and bring those points home tomorrow and add to the tally in the Power Stage if we can," he said.
The Lamia-based rally is making its return to the calendar for the first time since 2003.
(Reporting by Alan Baldwin in London, editing by Pritha Sarkar)