Evans must outscore Rovanpera at this weekend's first running of the asphalt event to take the title fight to the season finale in Japan next month.
The Toyota driver put up a stern fight on Friday recovering from starting the day in eighth overall to run as high as second behind his team-mate Rovanpera. But Evans was unable to match the Finn's speed in tricky wet conditions.
Evans dropped to third behind Hyundai's Thierry Neuville by the end of stage eight, 47.2s adrift of Rovanpera.
The Welshman declared Rovanpera did an "incredible job", admitting that his rival's pace wasn't all down to starting first on the road in the tough conditions.
"Clearly the gap is not going to be reachable by pure driving," Evans told Motorsport.com. "He has done an incredible job today.
"Of course, he made the use of his road position but also more than that, and in fairness he has done a really great job and I couldn't follow his speed.
"From our side we have to try and fight to get back in front of Thierry. We will continue to do the best we can until the end."
If the standings remain unchanged, Rovanpera will secure a second world title come Sunday but the Finn says the championship isn't always in his thoughts.
"It has been definitely tricky [today], but it is clear being first on the road should be good and we used our position quite well," said Rovanpera.
"In the afternoon, when the conditions were more equal, we were still quite fast.
"I don't really think about it [winning a second title] too much as there is quite a long way to go."
Ogier close to giving up after illness and puncture
While Rovanpera and Evans remain firmly in the hunt for victory, Sebastien Ogier will head into Saturday 2m35.9s adrift in sixth, after losing almost a minute to a puncture on stage three.
Ogier admitted after the incident that he had lost his "motivation", and later revealed that he is suffering from an illness that is making him feel dizzy behind the wheel.
"I have been a little bit better this afternoon, but definitely not at my best," Ogier told Motorsport.com. "Hopefully I will feel better after a good night's sleep.
"I'm not so sure what it is, but it is definitely affecting my head with a headache and concentration, and I feel a bit dizzy as well. It has been like this for some days.
"Today with the [tyre] problem as well, I was close to giving up, to be honest."
When asked about the puncture, he added: "I felt a little impact from nothing. I have just watched my onboard and you cannot do anything, it was a super narrow section where you just follow the line.
"There was a stone in the mud that was not to be seen in the recce, but it came out of the soft mud.
"There were many cars with broken wheels, but I had a puncture. It is hard to take for sure."