Lucas Pouille had lost every Australian Open match he played until he hired Amelie Mauresmo as coach.
A couple of months later, he's into a Grand Slam semifinal for the first time. Things will get tougher, though.
The 24-year-old Frenchman will next play Novak Djokovic, who is aiming for a men's record seventh Australian title.
Djokovic was leading 6-1, 4-1 and his quarterfinal match was less than an hour old Wednesday when eighth-seeded Kei Nishikori retired, finally succumbing after three of his four previous rounds went to five sets.
Pouille isn't even sure how far he's capable of going at Melbourne Park. But after losing in the first round on his five previous visits, he knows he's on the upward trajectory.
"I didn't win a match in Melbourne before coming here (this year)," Pouille said. "Now I'm in the semifinals. So just very, very happy."
Pouille fended off a strong comeback from 2016 Wimbledon runner-up Milos Raonic for a 7-6 (4), 6-3, 6-7 (2), 6-4 win, his first in three tries in a major quarterfinal.
He entered the match 0-3 against Raonic — including a first-round meeting here in 2016 — but targeted the big-serving Canadian's second serve and won points on 35 of the 62 he faced. Pouille also protected his serve, and was broken only once in the match.
Mauresmo, who won two major titles as a player, including the 2006 Australian women's title, had previously worked as Andy Murray's coach. Pouille said Mauresmo had quickly worked out how to improve his game.
"She's the right state of mind. She knows everything about tennis. It's not about being a woman or a man. It doesn't matter," Pouille said in an on-court interview when asked about the rarity of a highly-ranked male player working with a female coach. "You just have to know what you're doing — and she does."
The No. 28-seeded Pouille was up two sets and had break points in the seventh and ninth games of the third but Raonic held serve in clutch moments.
Then Raonic rallied, railing against officialdom after getting angry when he challenged a line judge's call as Pouille was serving to stay in the set.
His service return hit the baseline but was called out. When he challenged it, and a replay confirmed his shot was good, chair umpire Nico Helwerth ordered a replay of the point.
Raonic thought he deserved to be given the point and, when he asked why it wasn't awarded to him, told the umpire "because you don't watch, because you're incapable."
Pouille won the replayed point and held serve for 6-6, but Raonic won the first six points of the tiebreaker and eventually forced a fourth set.
It was on serve until Pouille put serious pressure on Raonic's serve and volleys, and broke to clinch the match.
Raonic is now 1-3 in Australian Open quarterfinals, but he had a tough draw at Melbourne Park. He had to hold off Nick Kyrgios in the first round, former champion Stan Wawrinka in the second and No. 4-seeded Alexander Zverev in the fourth.
Raonic said he was disappointed with his serve in the quarterfinals, but not about his challenge in the third set.
For Pouille, the Canadian had some words of wisdom.
"It's not so much only the opponent you're facing, but it's also the situation, which is a completely new one for him," Raonic said. "I think he has to stay true to himself, try to do the things he does well, really focus on that aspect more than anything else."