What will it take for Auger-Aliassime to shock Sinner?

Felix Auger-Aliassime is a huge underdog in Friday night's US Open semifinal match against Jannik Sinner, but not everyone is counting the Canadian out.  

"I'm picking Felix in five [sets] just because, you know, no one's saying it," said 2004 US Open doubles champion Daniel Nestor with a grin. "It's got that New York Giants - Patriots feel."

Back in 2008, the Giants spoiled the Patriots' quest for a perfect season with a shocking Super Bowl upset.

Sinner isn't going for a perfect season, but it's close. He claimed titles at the Australian Open and Wimbledon, and held three championship points in the French Open final before losing an epic to Carlos Alcaraz.

With a win on Friday, Sinner will become only the fourth man in Open Era to reach the final at all four Grand Slams in a season, joining Rod Laver (1969), Roger Federer (2006-07, 2009) and Novak Djokovic (2015, 2021, 2023).

Sinner is the defending US Open champion and has won 26 straight Grand Slam matches on hard courts. One more win and he'll tie Djokovic (2011-12) for the second-longest streak in history behind only Federer (40 straight from 2005-08).

Before losing 6-1, 6-1, 6-1 to Sinner in the fourth round, No. 23 seed Alexander Bublik joked that the 24-year-old Italian is like an AI-generated player.

"Some of it is just the complete absence of weakness," said Tennis Channel analyst Jon Wertheim when asked what impresses him most about Sinner. "He might be one of the best movers on tour, and his groundstrokes are as good as anyone, and his serve is really good. If you fashion a game plan, you sort of think to yourself, 'How in the world am I going to get to this guy?'"

Auger-Aliassime didn't come close in his last match against Sinner, falling 6-0, 6-2 in Cincinnati on Aug. 14.

But big upsets do happen. Three Canadian men have beaten a World No. 1, including Auger-Aliassime, who took down Alcaraz twice late in the 2022 season. Vasek Pospisil toppled Andy Murray at Indian Wells in 2017.

Nestor is the only Canadian to upset a World No. 1 in a best-of-five match, having beaten Stefan Edberg at a 1992 Davis Cup tie. It will take something truly special for Auger-Aliassime to follow in his footsteps.

"Definitely he does have to do something extra," said Nestor, who lifted 12 Grand Slam titles before retiring in 2018. "I think the reason Felix is in the position he is [in] is because he's made a commitment to be a little more aggressive. He's going to have to do that."

Auger-Aliassime fired 50 winners in a four-set upset win over No. 3 seed Alexander Zverev in the third round. He landed 42 more in a three-set win over No. 15 seed Andrey Rublev in the fourth round. He will need to amplify that type of form against Sinner.

The serve is also key. Auger-Aliassime is second in tournament aces with 69 behind only American Taylor Fritz, who hit 74 before getting knocked out by Djokovic in the quarter-finals.

Auger-Aliassime is winning 79 per cent of his first-serve points at this US Open and will need to maintain that level.

"But then he also has to take a little bit of risk on the second serve," said Tennis Canada's vice-president of high-performance Guillaume Marx, who coached Auger-Aliassime during his early days on tour. "He has to go for the serves and be very aggressive as well."

Marx points out Sinner effectively limited Alcaraz's ability to attack his second serve in the Wimbledon final. Auger-Aliassime must look to mimic that approach and quickly shake off any double faults that follow.

If the 25-year-old from Montreal can consistently hold serve, he'll have a chance even if he struggles to break Sinner, who is winning 84 per cent of his first-serve points, tied for second in the tournament with Alcaraz.  

Auger-Aliassime is 6-0 in tiebreaks in the tournament and won his last eight overall.

Once the rallies start, there are ways to put Sinner under pressure.

"You got to stretch Sinner into the forehand corner," said 1997 US Open finalist Greg Rusedski.

"As we saw with [Grigor] Dimitrov at Wimbledon, when he used that really knifing slice low and was willing to take it on, Jannik looked uncomfortable out there. And that's something that Felix has done pretty well throughout these championships. He's been willing to come forward. He's used the slice; the backhand has been better."

Dimitrov led Sinner 6-3, 7-5, 2-2 in a fourth-round match at Wimbledon before being forced to retire. Can Auger-Aliassime replicate what the Bulgarian did well?

"In the past I've seen him, you know, give a lot of free points away on the backhand, but this week has just been super solid on that side," said Canada's Davis Cup captain Frank Dancevic, who was in attendance for the wins over Zverev and Rublev. "He's using a slice more. He's staying in the points. He's waiting for the right balls to be able to attack."

Everything seems to be clicking for Auger-Aliassime in New York right now.

"He's just got to use his confidence," Dancevic said. "When Felix is hot like this, and he's playing well and he's using his weapons well, it's really tough to beat him."

Auger-Aliassime has flashed this form before. He reached the US Open semifinal in 2021, which is his only other appearance at this stage of a major. He helped Canada win the Davis Cup in 2022 and rose all the way to No. 6 while leading the tour in hard-court wins. He also beat Sinner twice in 2022.

Injuries and inconsistency slowed Auger-Aliassime's progress in recent years. He failed to advance past the second round in the past five majors.

But the potential has always been obvious. As an 18 year old in 2019, he became the youngest top-25 player since Lleyton Hewitt (18 in 1999). Hewitt went on to win the 2001 US Open.

So, why not now for the big breakthrough for Auger-Aliassime?

"Let's see an upset," Nestor said. "Let's see a first Canadian win a singles Grand Slam on the men's side."

Milos Raonic is the only Canadian man to reach a singles Grand Slam final. He lost to Murray in the 2016 Wimbledon championship match.

Bianca Andreescu claimed Canada's only singles Grand Slam trophy at the 2019 US Open.

Nestor believes Auger-Aliassime's movement and athleticism make him well-suited for this era of men's tennis. He can go the distance physically.

"Felix is built for this, you know, seven matches, three out of five," Nestor said. "It's going to be tough, for sure, but he's worthy of this position beating three players that are top 15 in the last few rounds."

It's been 28 years since Rusedski, also from Montreal, became the only Canadian-born man to reach the US Open championship match in the Open era.

"I'm hoping synergy works for Auger-Aliassime here and he can find a way to make his first major final," said Rusedski, who played under the British flag starting in 1995. "He's too good a player not to get there [one day], but he's got the ultimate test coming up."