A year since Rafael Nadal scrambled calculations for the Australian Open by quitting with a hip injury in the quarters, Kei Nishikori did likewise on day 10 when he handed Novak Djokovic a free pass into the last four.

The world No 1 plays Lucas Pouille on Friday night after leading 6-1, 4-1, when Nishikori, one of the most physically fragile players on the Tour, found the pain of a quad strain too much to bear.

“After third game or fourth game when I was serving, I felt pretty heavy to my right leg,” Nishikori said. “After that I couldn’t really bend my knees and couldn’t jump up. I decided to stop.”

The match itself revealed little, although Djokovic will be glad of the rest. The Serb, who has been growing in confidence, will shorten in favouritism to win a record seventh title, in the absence of Roger Federer, rudely bumped out by Stefanos Tsitsipas, who plays Nadal on Thursday night.

If Nadal were to collapse again (he withdrew from the Brisbane Open to protect a knee injury), further chaos would disturb the final weekend.

John McEnroe spread some of his anarchic charm earlier during his on-court interview with Pouille. “I’m getting the feeling that a lot of these guy players are going to be hiring female coaches now,” he said to the Frenchman after he had beaten Milos Raonic in the earlier quarter-final. Pouille, who is coached by Amélie Mauresmo was unimpressed, and replied: “They should, they should … It’s not about being a woman or a man: it doesn’t matter. You just have to know what you’re doing and she does.” It is a sentiment that would have resonated with Andy Murray, who was also coached by Mauresmo. Pouille added: “Men are coaching women, so why not the contrary? I mean, they don’t get it. She’s a champion. She’s a great coach.”

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One of the least-mentioned plus points of this shredded Australian Open men’s draw is the uncertainty injected into it by the random fall of favourites. The received wisdom was that the Canadian with the golden arm would bring too much power with ball in hand for the Frenchman with the cultured groundstrokes – nurtured in many practice sessions with Roger Federer – but it did not quite work out that way. Pouille prevailed 7-6 (4), 6-3, 6-7 (2), 6-4 in just over three hours to earn his first slam semi-final place.

Early intelligence on this quarter-final was mixed. While Pouille sat 14 points adrift of Raonic in the rankings at 31, there were doubts about the big man’s fitness given the number of times he had had to quit the Tour in the past with a hospital log of injuries.

Then he put 30 aces past Nick Kyrgios in the first round, but the Australian reckoned the super-server’s chances of winning the title were not as strong as the numbers suggested. “There are players that are much better than I am, who can neutralise big servers so easily with the chip return, which I don’t have. [Raonic’s serving] would have beaten a lot of players, for sure. I probably would have beaten 75% of the draw today. But Milos played scary.”

Raonic continued to play scary all the way to the quarter-finals, leading the tournament’s big hitters with 107 aces. The quickest of his new batch on Wednesday was 139 mph, as his pre-injury aura returned. The free points kept flowing, and Pouille soaked them up with the sort of defensive skills Kyrgios referred to.

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Once he had clawed back Raonic’s 5-2 lead in the second set, he seemed to have the match under control after an hour and a half, but the contest see-sawed once more as Raonic forced the tie-break that kept him in the fight, closing the gap after wasting two of six set points to force a fourth set.

Pouille, too, had been profligate. He had not been able to cash in on four break points in the ninth game of that third set and might have wondered if his window had been opened and closed. He was within touching distance of moving into the semi-finals, a victory in itself, whatever the result there.

In three previous contests with the Canadian, Pouille could not win a set. In the space of two winning sets, he looked like sending him home in double-quick time. But, while he had only once in his career come from two sets down, Raonic is so often underestimated. Nobody expected him to beat Alexander Zverev, and he did so – comfortably.

Yet Pouille did not represent as imposing a threat as others in the quarters, having struggled for more than 12 hours to reach the final 16 of a slam for the third time. He was a losing quarter-finalist at Wimbledon three years ago, and in New York later that year.

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The end was tight. Raonic was given the ball again at 4-5. Surely, went the theory, he would add to his aces tally, level it up and go on to victory in a fifth set. Pouille, though, chipped and teased his way to two match points, forcing Raonic to push a final backhand wide.

Raonic ended up with 132 aces, way more than anyone left in the draw – but he is not alongside his peers still competing for a bigger prize. While Pouille’s tally of free-serving points – 84 – puts him a respectable fifth in the field, he will bring a bit more than raw intimidation to the semi-finals.

Only six Frenchmen in the modern era have reached this stage. Pouille is the first since Jo-Wilfried Tsonga in 2010. To get there that year, he beat Djokovic, then lost to Federer in the semi-final, the Swiss going on to beat Murray in the final. It all seems so long ago.