Championship leader Rovanpera started the day third, 25.5s adrift, but returned to the service park with a 2m04.4s rally lead over Hyundai’s Dani Sordo.
Hyundai’s Neuville retired from the lead on the afternoon’s first stage handing the advantage to Ogier.
However, the Toyota driver then lost four minutes to a suspension issue on the afternoon’s last test, dropping the Frenchman to fourth overall.
As a result of the late drama, Toyota’s Elfyn Evans ended the day in third (+2m09.4s) after dropping more than a minute to overheating issues on his GR Yaris on Saturday morning.
M-Sport’s Ott Tanak inherited fifth (+4m49.7s), hampered by a 3m40s penalty on Friday after being late from a tyre fitting zone due to a water pump issue.
Hyundai’s Esapekka Lappi brought a wounded i20 N through the day’s final stage in sixth, ahead of Toyota’s Takamoto Katsuta, who suffered a pair of punctures during the afternoon.
The afternoon loop started in dramatic fashion as rally leader Neuville’s hopes of repeating last year’s Acropolis victory vanished on stage 10 (Pavliani, 24.25km).
The Belgian struck a hole in the road which bent his front right wheel and damaged the suspension beyond a roadside repair.
Neuville’s demise handed the rally lead to Ogier, who managed to complete the stage with the second-fastest time behind pacesetter Rovanpera. The roads were much drier compared to the first pass but were even rougher.
Sébastien Ogier, Vincent Landais, Toyota Gazoo Racing WRT Toyota GR Yaris Rally1
Photo by: McKlein / Motorsport Images
Rovanpera edged Ogier by 0.2s to reduce the gap to the new rally leader to 12.6s.
Sordo inherited third position (+1m48.2s) with the Spaniard, 1.6s ahead of Evans, who dropped a minute with a suspected overheating issue on his GR Yaris in the final stage of the morning loop.
Toyota was able to rectify the issue during the midday service to allow Evans to post the third fastest time on stage 10.
Greece’s rough gravel roads continued to bite in stage 11 (Karoutes) as Lappi and Katsuta were both delayed by problems.
Katsuta dropped 4m35.7s after stopping twice to change punctured front left and right tyres. The delay was enough to allow Lappi to pass the Japanese driver on the stage, although the Finn’s car wasn’t in rude health, thanks to an alternator failure and a transmission issue.
The issues brought Tanak back into a fight, moving to fifth ahead of Katsuta and Lappi.
At the front, the battle for the victory raged on with Rovanpera again pipping Ogier by 0.2s to win the stage, closing to within 12.4s of the Frenchman.
There was more positive news for Toyota as the recovering Evans leapfrogged Sordo by 4.1s to create a 1-2-3 in the overall standings for the Japanese brand. The position change came despite Evans suffering a tyre off the rim towards the end of the stage.
The final stage of the loop (Eleftherochori, 18.02km) offered yet another twist as Ogier became the last driver to pick up a mechanical problem on the abrasive roads.
The Frenchman suffered left rear suspension failure and a puncture, costing the eight-time world champion the lead and four minutes in the process, demoting him to fourth overall.
Ogier was able to limp to the stage end and was seen working on his car to allow him to make the 27-kilometre drive to the Lamia serviced park.
Team-mate and new rally leader Rovanpera took the stage win by 12.9s from Sordo.
“It was a nice battle, of course not the easiest to push with Seb because we had the championship to push for. I think we had a good day, we were fast but we also kept the car in one piece,” said Rovanpera.
In WRC2, Andreas Mikkelsen completed Saturday’s stages with a 0.4s lead over Gus Greensmith.
The rally will conclude following Sunday’s three stages.