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Greece's #NextGenATP star Stefanos Tsitsipas enjoyed a breakout season on the ATP World Tour.

Top Five #NextGenATP Moments From 2018

ATP Tour Season In Review: Five Best #NextGenATP Moments In 2018

Continuing our Season In Review series, ATPTour.com looks at the top five #NextGenATP moments from 2018.

5. Denis Shapovalov makes the Mutua Madrid Open semi-finals
By May, Canada's top #NextGenATP star Denis Shapovalov was, without a doubt, a known commodity. In 2017, he became the youngest ATP World Tour Masters 1000 semi-finalist at the Coupe Rogers in Montreal, made the fourth round of the US Open and qualified for the inaugural Next Gen ATP Finals.

And in 2018, his historic efforts didn't slow down. In Madrid, Shapovalov, who had zero ATP World Tour clay-court wins before the tournament, beat countryman Milos Raonic and Brit Kyle Edmund, who had reached the Australian Open semi-finals months earlier.

Shapovalov, in reaching his second Masters 1000 semi-final, became the youngest semi-finalist in Mutua Madrid Open history. The 19-year-old left-hander finished 2018 by cutting his year-end ranking nearly in half, from No. 51 to No. 27.

Watch Hot Shot: Shapovalov Rips Backhand Winner Past Raonic In Madrid

4. Frances Tiafoe wins maiden tour-level title at the Delray Beach Open
Frances Tiafoe grew up idolising Juan Martin del Potro. The Argentine was the first player to sign a ball for Tiafoe when he was a boy attending the Citi Open in Washington, D.C.

But at the Delray Beach Open in February, Tiafoe blocked all of that aside and upset the second seed en route to the best week of his career. Tiafoe beat Aussie Matthew Ebden, Del Potro, 2017 Next Gen ATP Finals champion Hyeon Chung, Shapovalov and Germany's Peter Gojowczyk to win his maiden ATP World Tour title.

And to think, the American almost didn't even have a spot at the ATP World Tour 250-level event. Tiafoe forgot to sign up by the entry deadline, but the tournament gave him a wild card, and both parties were pleased they did. Tiafoe went onto make his debut at the Next Gen ATP Finals and finish at a personal year-end best No. 39 in the ATP Rankings.

Watch Highlights: Tiafoe Wins First Title In Delray Beach

3. Stefanos Tsitsipas wins the Next Gen ATP Finals on debut
At the start of the year, neither player was in the Top 90 of the ATP Rankings, hardly making them favourites to reach the title match of the Next Gen ATP Finals, where eight of the world's best 21-and-under players finish their seasons in Milan. But Stefanos Tsitsipas of Greece and Aussie Alex de Minaur were two of the most improved players on tour in 2018, and they showed their elevated games all week at the Fiera Milano.

Read More: Tsitsipas Named Most Improved Player Of The Year

Tsitsipas and De Minaur both reached the final bidding for a perfect 5-0 week. But Tsitsipas, behind some of his best serving all season, overpowered the 19-year-old Aussie in the highly-pressurised environment 2-4, 4-1, 4-3(3), 4-3(3). Tsitsipas won 72 per cent of his service points (54/72), and outhit the scrappy De Minaur, who saved seven of eight break points.

On match point, Tsitsipas fell to the ground, his hands shielding his eyes. It was almost as if the 20-year-old couldn't believe the transformation he'd undergone in the past 12 months. At the 2017 Next Gen ATP Finals, Tsitsipas, then No. 87, was an alternate in the eight-man field. But this year, he was the champion.

Watch Highlights: Tsitsipas Beats De Minaur For Milan Title

2. Alex de Minaur starts strong Down Under
You could not have blamed tennis fans, even those living in Australia, for thinking it might be a couple years before Alex de Minaur made his march to the Top 50 of the ATP Rankings. In January, the 18-year-old was ranked No. 208, and, although he won his first tour-level matches in Australia in 2017, he had experienced little success away from his home continent. 

But mentor and former World No. 1 Lleyton Hewitt kept telling De Minaur to believe in himself, that he had the game to compete with the best. De Minaur made Hewitt look like a smart man during all of 2018, and it started with his win over former World No. 3 Milos Raonic at the Brisbane International in January.

De Minaur had been 0-2 against Top 40 opponents, but he routed Raonic 6-4, 6-4 in front of thousands of proud Aussies for back-to-back tour-level wins (d. No. 44 Steve Johnson in first round).

De Minaur would go onto make the Brisbane International semi-finals and the Sydney International final (l. to Medvedev). By the end of 2018, he'd make the biggest jump in the Top 50, finishing the 2018 season at No. 31 and as the top-ranked Aussie. The Sydney native was also voted by his peers as the ATP Newcomer of the Year in the 2018 ATP World Tour Awards Presented By Moët & Chandon.

Watch Feature: Hewitt Belief In De Minaur Paying Off

1. Stefanos Tsitsipas makes history in Toronto
Greece's #NextGenATP star Stefanos Tsitsipas had enjoyed big wins before the Rogers Cup in August, including when he made the Barcelona Open Banc Sabadell final in April. But never before had the right-hander turned in such a week like he did at the ATP World Tour Masters 1000 event in Canada.

His best week started by beating No. 8 Dominic Thiem and was followed by his three-set win against Novak Djokovic, who was fresh off his fourth Wimbledon – and 13th Grand Slam – title. Yet the Serbian was broken in the second game of the final set and never recovered, as Tsitsipas moved into his first Masters 1000 quarter-final.

Watch Highlights: Tsitsipas Surprises Djokovic With Dropper

The firsts would only keep coming. Next, Tsitsipas avenged his straight-sets loss to Alexander Zverev at the Citi Open only a week earlier by saving two match points and hitting 28 winners – 18 from his forehand – in their quarter-final. Zverev served for the match at 6-3, 5-3, but Tsitsipas broke and erased both match points in the tie-break and advanced 3-6, 7-6(11), 6-4.

In the semi-finals, Tsitsipas came back from a set down once more, beating Wimbledon finalist Kevin Anderson 6-7(4), 6-4, 7-6(7) before falling to No. 1 Rafael Nadal in the final. Tsitsipas would finish the season No. 15 in the ATP Rankings and with the Nitto ATP Finals in mind as a 2019 goal.