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Andrey Rublev's win against Western & Southern Open champion Grigor Dimitrov at the US Open was among the biggest Grand Slam upsets in 2017.

Five Biggest Grand Slam Upsets of 2017

ATP World Tour Season In Review: The Biggest Upsets at Grand Slams

Continuing our Season In Review series, ATPWorldTour.com revisits the five biggest Grand Slam upsets of 2017.

(5) Andrey Rublev d. Grigor Dimitrov 7-5, 7-6(3), 6-3 – US Open Second Round

Grigor Dimitrov had arrived, again. After reaching the Top 10 of the Emirates ATP Rankings in 2014, the Bulgarian was back among the elite this August and again a favourite to make a deep run at Grand Slams. A week before the US Open, Dimitrov had won his maiden ATP World Tour Masters 1000 title at the Western & Southern Open in Cincinnati. The seventh seed was a trendy pick to reach the second week in Flushing Meadows.

Read More: Rublev Honest After Tough Loss In Milan

But #NextGenATP Russian Andrey Rublev had been quietly building an impressive season, and the 19-year-old didn't lie down for Dimitrov. Rublev fell behind a break in the first and second sets but came back in both sets, feeding Dimitrov a steady barrage of heavy forehands. He finished with 36 winners, including 23 on the forehand side. Rublev was also clutch on his serve, erasing eight of 10 break points.

The win was the Russian's first Top 10 victory. He'd go to on reach the quarter-finals in New York (l. to eventual champion Nadal), becoming the youngest US Open quarter-finalist since Andy Roddick in 2001.

The run also solidified Rublev's status as one of the top #NextGenATP players in the world. The right-hander later reached the final of the inaugural Next Gen ATP Finals (l. to Chung).

(4) Daniil Medvedev d. Stan Wawrinka 6-4, 3-6, 6-4, 6-1 – Wimbledon First Round

Daniil Medvedev checked a number of boxes by beating Stan Wawrinka at SW19. Before playing fearlessly to beat the Swiss right-hander, the 21-year-old had never won a match at a Grand Slam, beaten a Top 5 player or even played a match at Wimbledon.

The #NextGenATP Russian picked the perfect setting for the career breakthrough: Centre Court. After splitting the first two sets with Wawrinka, Medvedev gained the crucial break at 5-4 to take the third set against the three-time Grand Slam champion.

In the fourth, the Russian rolled, hitting four aces and converting both break points to advance.

Wawrinka, who was eyeing a career Grand Slam at The Championships, has struggled at Wimbledon. But he was coming off a final run at Roland Garros and had brought on Pete Sampras' former coach Paul Annacone to help as part of his coaching team during the grass-court swing.

But the Swiss star was also battling a knee injury. His match against Medvedev was his final contest of the 2017 season.

(3) Fernando Verdasco d. Alexander Zverev 6-3, 3-6, 6-4, 6-2 – Roland Garros First Round

This was Alexander Zverev's time to make a splash at a Grand Slam. The 6'6” right-hander had beaten Novak Djokovic for the Internazionali BNL d'Italia title in Rome weeks earlier. The win had given Zverev his first ATP World Tour Masters 1000 title and a spot in the Top 10 of the Emirates ATP Rankings at No. 10. The right-hander looked ready to battle deep into the second week of Grand Slam tournaments.

His first-round opponent, however, was no debutant. Spanish veteran Fernando Verdasco had conquered bigger odds in the past – see his 2016 Australian Open first-round upset of Rafael Nadal – and Verdasco is never one to be intimidated against a higher-ranked player.

The 33-year-old broke the German eight times in the two-hour and 52-minute contest that spanned two days because of darkness. Play was suspended after two sets, and Zverev looked ready to take control of the match when play resumed, gaining a 3-1 lead in the third set.

But Verdasco fought back and broke the 20-year-old's will, winning five of the third set's final six games to lead two sets to one. The left-hander cruised in the fourth set to gain a 2-1 lead in their FedEx ATP Head2Head series.

“Winning the third set gave me a lot of confidence... and I think it was hard for him on the other side, to start again and have to win two more sets,” Verdasco said.

The Spaniard, who was making his 56th consecutive Grand Slam appearance, improved to 13-1 in Roland Garros first-round contests.

(2) Mischa Zverev d. Andy Murray 7-5, 5-7, 6-2, 6-4 – Australian Open Fourth Round

It had been eight years since Andy Murray lost at the Australian Open before the quarter-finals. The Scot had reached the Melbourne final five of those times, a semi-final in 2012 and a quarter-final in 2014.

Throw in the fact that Murray had won 32 of his past 33 matches, dating back to his perfect 2016 finish, and you can easily see why the Brit was the heavy favourite during his fourth-round match against Mischa Zverev. But the German's serve-and-volley game presents a different look for players, and Murray struggled all day against the aggressive left-hander, who was eager to make the most of his first Grand Slam fourth round appearance.

The German attacked the net 118 times against the top seed, winning 55 per cent of those points (65/118). He also mixed up his groundstrokes, slicing often to prevent Murray from gaining rhythm.

It didn't matter how many times Zverev got passed at the net or how many times he missed a volley — the 29-year-old was committed to his game plan, and he never wavered.

“There was no Plan B, really,” he said. “I can't stay on the baseline, a couple feet behind the baseline, try to out-rally him. He's very strong physically. He has a good baseline game. I knew I had to come in. That was my only chance to win.”

The victory marked a successful turnaround for Zverev. In March 2015, he was No. 1,067 in the Emirates ATP Rankings. Less than two years later, he was playing in the quarter-finals of the Australian Open (l. to eventual champion Roger Federer).

(1) Denis Istomin d. Novak Djokovic 7-6(8), 5-7, 2-6, 7-6(5), 6-4 – Australian Open Second Round

The Serbian was The King of Melbourne. Novak Djokovic had won five of the past six Australian Open titles. The only year he didn't win during that stretch – 2014 – the right-hander was knocked out in the quarter-finals by eventual champion Stan Wawrinka of Switzerland.

In his most recent Grand Slam, the US Open, Djokovic also performed well, reaching the final in New York (l. to Wawrinka). Suffice to say, the Serbian was feeling good in the world's biggest stadiums.

World No. 117 Denis Istomin, on the other hand, had never performed exceptionally well at Grand Slams. His best result had been two fourth-round runs – at 2012 Wimbledon and 2013 US Open.

But the wild card from Uzbekistan picked the right time to play the match of his life. As Djokovic acknowledged after the upset, Istomin did just simply outplay the World No. 2, playing bigger in the crucial moments and outrallying one of the most consistent players of all-time.

“All the credit to Denis for playing amazing,” Djokovic said. “He deserved to win. No doubt, he was a better player in the clutch moments. He stepped it up, played aggressive. Served very well, very precise. There's not much I could do. Of course, I was not pleased with my performance overall. But I have to congratulate my opponent today.”

Istomin ended Djokovic’s 15-match win streak at Melbourne Park. The Serbian had only lost once to a player ranked outside of the Top 100 in the Emirates ATP Rankings during the past seven years – No. 145 Juan Martin del Potro in the opening round of the 2016 Rio Olympics.

The stunner was Djokovic's earliest loss at a Grand Slam championship since his 2008 Wimbledon second-round exit to Russian Marat Safin. The loss also marked the first time that Djokovic had gone three Grand Slam championships without picking up a title, since between 2013 Roland Garros and 2014 Wimbledon.