Evans inherited a 19.1s lead on Saturday morning after Friday’s pacesetter Thierry Neuville retired for the day after crashing out in stage 11 in the morning loop.
However, Evans faced a stern challenge from Tanak in the afternoon, who reduced the gap to 12.5s before a mechanical issue struck his car in the day's penultimate stage.
Hyundai’s Esapekka Lappi struggled for outright pace throughout, but held onto a comfortable third, 55.4s adrift in the sole remaining i20 N.
Toyota’s Sebastien Ogier managed to haul himself from seventh to fourth courtesy of three stage wins across the day, but is only 2.0s ahead of his world champion team-mate Kalle Rovanpera.
Ogier suffered a 10s penalty for checking into the day’s opening stage late after having to fix a problem on his GR Yaris, due to an error in service, on a road section. This came on top of a minute penalty for a safety belt infringement issued on Friday night.
Rovanpera closed the gap to Ogier after making the most of his advantageous road position to set fastest times in four of the eight stages.
The Finn leapfrogged team-mate Takamoto Katsuta and M-Sport-Ford’s Pierre-Louis Loubet, who completed Rally1 runners.
Crews faced far more slippery road conditions for the second pass of the day’s stages, thanks to gravel brought onto the tarmac from the many cuts littered on the route.
Ogier was among those to be caught out by the gravel as he overshot a hairpin, but incredibly he was able to recover to set the fastest time on stage 13. The Frenchman’s speed was enough for him to climb to fourth overall ahead of Loubet.
The eight-time world champion wasn’t the only driver to hit trouble as Lappi suffered a half spin at a tight left hander, while Rovanpera also had a small spin at a junction.
Lappi dropped 16.6s aș a result of the spin while Rovanpera reached the finish 1.6s slower than pacesetter Ogier to move into sixth overall ahead of team-mate Katsuta.
The major talking point was the fight for the rally lead as Evans' margin over Tanak was reduced to 15.9s.
Tanak managed to avoid trouble in the stage to clock the second fastest time, 0.4s slower than Ogier. Evans, struggling for confidence driving what he declared a “skittish” GR Yaris dropped 7.1s in the stage.
This lead battle intensified in stage 14, a short yet picturesque technical run from Vinski Vrh to Duga Resa.
Tanak produced an on the limit drive to clinch his second stage win of the event to pip the benchmark set by Rovanpera by 0.9s. Tanak was able to claw 3.4s from Evans, reducing the gap to a surprised Welshman to 12.5s.
"I can believe he's on the limit with that time,” said Evans. “For me it was a clean run to be honest, I'm surprised to lose that much."
There was further movement on the leaderboard as Rovanpera's time moved the Finn ahead of Loubet into fifth overall as he closed to within 3.7s of fourth-placed Ogier.
The penultimate stage saw the lead battle swing back towards Evans as the Toyota driver benefitted from a mechanical issues for Tanak, who was without the use of his handbrake. The result was 4.3s gain for Evans, who extended his lead back out to 16.8s.
“Quite a f****** disaster. Handbrake is not working and things like this so it is tricky when it is shitty like this,” said a frustrated Tanak at stage end.
"I didn't think it would be enough again to be honest,” added Evans. “I felt like I was pushing harder in the previous one - so maybe that's where I'm going wrong!.”
Rovanpera emerged as the stage winner, which heaped pressure on Ogier in the fight for fourth, with 1.3s separating the pair.
Tanak’s mechanical problems continued into the final stage of the day, resulting in the Estonian dropping a further 8.6s to Evans, who wasn’t happy with his own performance to end the day with the fourth fastest time in stage 16.
Ogier took the stage honours to respond to Rovanpera’s push, beating his team-mate by 0.7s as the battle for fourth overall raged.
Yohan Rossel held a 11.5s lead over Nikolay Gryazin in WRC2. The rally concludes on Sunday after four stages, totalling 54.48 kilometres.
