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Juan Martin del Potro pulled off a comeback for the ages at the US Open.

Biggest Grand Slam Comebacks Of 2017

ATP World Tour Season In Review: Biggest Grand Slam Comebacks

Continuing our Season In Review Series, ATPWorldTour.com revisits the biggest Grand Slam comebacks of 2017:

5. Andreas Seppi d. Nick Kyrgios 1-6, 6-7(1), 6-4, 6-2, 10-8 - Australian Open 2R

There seems to be a special connection between Andreas Seppi and the Australian Open. Three years ago, the Italian saved a match point to upset Lleyton Hewitt in a five-set thriller at the Australian Open. Then, in 2015, he would advance to the Round of 16 with a stunning four-set dismissal of Roger Federer - his first Top 10 win at a Grand Slam.

As Seppi began to battle back from a two-set deficit against home hope Nick Kyrgios in this year's second round, another moment of magic was in the cards. In front of a packed crowd on Hisense Arena, Seppi took the third set 6-4 and the fourth set 6-2 and it quickly became apparent that the Italian would deliver even more heartbreak to the Aussie faithful. 

In 2015, Seppi had fallen to Kyrgios 8-6 in a decider after racing to a two-set lead. The 33-year-old was ready to repay the favour. He would deny a match point while serving at 8-7 in the fifth set with a rifled forehand winner and snatched the decisive break in the next game. Seppi's 16th ace would seal the 1-6, 6-7(1), 6-4, 6-2, 10-8 victory after three hours and nine minutes.

“I remember the match from two years ago – it was pretty much the same,” said Seppi. “I knew what's going to happen, what it was going to be like on the court. It's always very, very tough to play in a crowd like this or stadium like this. But it was a great atmosphere.

“I just was focusing on my game. I served for the match before, lost my serve. I just tried to refocus, play like I did before. On match point, it was a big shot down the line. Maybe it was meant to be.”

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4. Janko Tipsarevic d. Thanasi Kokkinakis 6-7(5), 3-6, 6-1, 7-6(2), 6-3 - US Open 1R

For nearly two years, Janko Tipsarevic found himself outside of the Top 300 in the Emirates ATP Rankings. Recurring foot problems kept the Serbian on the sidelines for extended periods, but the former World No. 8 never gave up hope.

As Tipsarevic continued to fight towards a return to the Top 50 of the Emirates ATP Rankings at the US Open, that resilience was on full display. In a first-round marathon on Court 17, the Belgrade native clawed back from a two-set deficit to deny #NextGenATP Aussie Thanasi Kokkinakis 6-7(5), 3-6, 6-1, 7-6(2), 6-3 in four hours and 10 minutes.

Kokkinakis, who was in the midst of his own comeback quest following a multitude of injuries, did well to save 16 of 22 break points faced, but Tipsarevic's experience guided him past the finish line. The 33-year-old was denied three match points with Kokkinakis serving at 5-2 in the decider, but would close it out on his fifth chance in the next game.

Tipsarevic, a nominee for the Comeback Player of the Year Award in the 2017 ATP World Tour Awards Presented by Moët & Chandon, was sitting outside the Top 250 one year prior. But a quartet of ATP Challenger Tour titles in 2017 - two in Thailand and two in China - saw the Serbian vault back inside the Top 60. He completed a perfect 20-0 campaign on the circuit. Moreover, the comeback victory over Kokkinakis was his first from two sets down in five years.

3. Ivo Karlovic d. Horacio Zeballos 6-7(6), 3-6, 7-5, 6-2, 22-20 - Australian Open 1R

Ivo Karlovic said that, long after he retires, this is one match he will never forget. Neither will we.

Court 19 at Melbourne Park could barely contain the drama that was unfolding in its modest confines, as Karlovic and Horacio Zeballos battled for five hours and 14 minutes in a marathon first-round encounter. Karlovic rebounded after dropping the first two sets to claim a stunning 6-7(6), 3-6, 7-5, 6-2, 22-20 victory. The 42-game deciding set alone lasted two hours and 41 minutes, with the Croatian saving a break point at 3-2 and the Argentine denying one at 11-11, before Karlovic finally closed the door with a break at 21-20 30/40.

The thriller spanned 84 games in total, breaking the Australian Open record since the introduction of the tie-break in 1972. It surpassed Andy Roddick and Younes El Aynaoui's 2003 classic of 83 games. Only Novak Djokovic's win over Rafael Nadal in the 2012 final was longer by time played, at five hours and 53 minutes.

“This match is what I will, after my career, remember,” said Karlovic. “If it was an easy match or I lost easily, I wouldn't remember it. But this one I will definitely remember forever. 

“My arm is good, but my knee, my back a little bit, is not so good,” said Karlovic. “I was just trying to hang in there, just point by point… [As the fifth set wore on], actually I was thinking about that other match: [John] Isner versus [Nicolas] Mahut (at 2010 Wimbledon, which Isner won 70-68 in the fifth set). I was hoping, a little bit, it could go that long so I could also have that record.”

Karlovic's 75 aces is another Australian Open record, blasting Joachim Johansson's previous single-match mark of 51, which was set in 2005.

In addition, it was just the third 0-2 comeback of the 38-year-old's career. His two previous victories both came against James Blake, rallying in the 2009 Davis Cup quarter-finals and in the 2013 US Open first round.

2. Mischa Zverev d. John Isner 6-7(4), 6-7(4), 6-4, 7-6(7), 9-7 - Australian Open 2R

John Isner and Mischa Zverev had faced off on two previous occasions entering the season, and both proved to be one-way traffic in favour of the American. So when Isner grabbed a two-set lead in their Australian Open second round encounter, it looked like much of the same. 

But 2017 would bare witness to a much improved Zverev and the German's impressive campaign kick-started with this riveting comeback at Melbourne Park. After dropping the first two sets in tie-breaks, Zverev extended the match to a fourth, where he would fight back from a break down at 4-2 and turned aside a pair of match points. The first was saved as he served to stay in the encounter at 5-4 and the second was denied at 7/6 in the ensuing tie-break.

The match would progress to a decider, where Isner saved three straight match points of his own at 6-5, but the big-serving American was unable to deny a fourth at 8-7. A rifled return at Isner's feet pushed the German across the finish line after four hours and 10 minutes. The 30-year-old Zverev notched the first comeback from two sets down in his career and his first five-set victory in a decade (2007 Wimbledon qualifying). He would finish 2017 with a perfect 4-0 record in five-setters.

"It was definitely my biggest win, especially coming back from two sets down," said Zverev. "Now being in the third round of the Australian Open, it was everything. I was emotional with my family being here and coming back from injury. It was big."

The match proved to be the catalyst for Zverev's strong season, which saw him stun World No. 1 Andy Murray just days later and included a first ATP World Tour final appearance in Geneva. He would go on to beat Isner on two other occasions, prevailing in the Geneva second round and US Open third round.

(1) Juan Martin del Potro d. Dominic Thiem 1-6, 2-6, 6-1, 7-6(1), 6-4 - US Open 4R

This was as good as it gets. We might might never see another comeback with such drama, such emotion and such grit and determination than the display Juan Martin del Potro and Dominic Thiem exhibited at the US Open. It was one for the ages.

Known as one of the more passionate and exuberant players on the ATP World Tour, Del Potro left it all on Grandstand court on a Tuesday evening in Flushing Meadows. Fighting a flu and a fever, the Argentine was barely able to move as he entered the court and with little range and rhythm, Thiem took advantage, blasting to a quick 6-1, 6-2 lead.

But the heavily partisan Argentine crowd, draped in blue and white, carried the 2009 champion. They urged on the lethargic and fatigued Tandil native and despite being on the verge of tears, he would respond in grand fashion. Bolstered by the crowd, he rewrote the script, halting Thiem's flood of momentum with a run of eight of the next 10 games.

Once again, the Austrian answered with a break in the fourth to take a 5-2 lead. He would serve for the match but Del Potro was far from finished, breaking back and eventually saving two match points - both with mammoth aces - while serving at 5-6. The drama boiled over to a fifth set, and as a rush of adrenaline surged through Del Potro, he would grab his second match point after three hours and 34 minutes.

"I don't know how I was able to win that match," del Potro said to ESPN in his post-match interview. "I was sick the last two days and I tried to play as best that I can. When I saw this crowd cheering for me, I was trying to feel better. I fought like this because of these guys."

It marked the seventh five-set victory in Del Potro's career and just the second comeback from two sets down. He would follow it up with a four-set upset of Roger Federer in the quarter-finals, reeling off 20 of 24 matches to finish the season and falling just short of qualifying for the Nitto ATP Finals.