Melbourne: Milos Raonic's machine-like advance through the Australian Open hit a brief glitch against Gilles Simon but the Canadian re-booted to delete the dogged Frenchman 6-2 7-6(5) 3-6 6-3 and reach the fourth round on Saturday.
The third seed, who revealed he has been suffering from a "bad fever", lost his first set of the tournament against the indefatigable Simon, whose hard running and sublime passing shots threatened to turn the game on its head.
"I've had a rough last 48 hours, everything was aching, just sort of those kind of symptoms," said Raonic.
"I'm managing it. I'm sure I'll probably get something after today's match."
His chances of blazing a trail to a maiden final in Melbourne were handed a huge boost when Uzbek journeyman Denis Istomin knocked out six-times champion Novak Djokovic in the second round. That upset has left Raonic as the highest seed left in the lower half of the draw.
Raonic has long been tagged a grand slam contender and he looked the part early on against Simon, mowing through the first set in 28 minutes and showing impressive composure to fend off the 25th seed in a tense tiebreak in the second.
The 26-year-old stumbled in the third as he gave up two breaks of serve but refused to put it down to two days battling illness catching up with him.
"He started playing a bit more aggressive, I became a little bit too passive," Raonic said.
"It was more just a dip in sort of dictating. It wasn't a physical dip of any kind."
He pushed a shot wide to give up a break-point at 4-3 and Simon grabbed the chance with a delightful drop-volley played off his feet.
Simon sealed the set with a thumping first serve that triggered raucous cheers from the French fans in Hisense Arena and sent Raonic back to his chair muttering.
The Canadian regrouped, however, and raced to 3-1 before stumbling again to lose serve a third time.
But he grabbed back the break and grimly held to close out a galvanising win before returning to his sick bed.
"The most important thing for me right now is just to get myself at full capacity or as close to it as possible," Raonic added.