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Roger Federer, Grigor Dimitrov, Nick Kyrgios and Rafael Nadal have gotten off to excellent starts in 2017.

Top Seven Stories Of 2017 So Far

ATPWorldTour.com recaps the storylines from the first quarter of the season

The season is only three months old but there's already a plethora of storylines to track. Here are the top seven stories of 2017 so far:

1. Roger Federer's Surprise Start

Federer, arguably the greatest player of all-time, has been the story of 2017. The Swiss star is still bringing his love for tennis that has helped millions of fans adore him. But Federer's ability to change might be the most impressive detail about his comeback so far. The right-hander has surprised and impressed most with his new flattened-out backhand, aided by his bigger, 97-inch racquet.

Heck, the fact that Federer still wants to tinker with his game – at 35 years old, in his 20th year on tour and with four kids and Mirka at home – is worth noting as well.

No one expected Federer to sprint to a 19-1 start and to beat Rafael Nadal three times, including during two finals – Australian Open and the Miami Open presented by Itau – and no one knows what the remainder of 2017 will hold for the 26-time ATP World Tour Masters 1000 champion. Maybe No. 1 in the Emirates ATP Rankings?

Federer's Best Starts To A Season

Year W-L Sunshine Double? Year-End Emirates ATP Ranking
2017 19-1  Yes ?
33-1  Yes No. 1
35-1  Yes No. 1
23-1  No No. 1

2. Rafael Nadal's Resurgence

Two of the biggest questions coming into 2017: How would Federer come back, and how would Nadal return after another injury? We know about Federer, and we now know about Nadal as well. The Spaniard has hit top form on the hard courts, reaching three finals – Australian Open (l. to Federer), Abierto Mexicano Telcel (l. to Querrey) and the Miami Open presented by Itau (l. to Federer) – and has posted a 19-5 record to start 2017, tying him with Federer for the most wins to date.

Perhaps most importantly, Nadal feels good about his team's new addition, Carlos Moya, and about his play. “I am at a very high level of tennis and I believe I am ready to win titles,” Nadal said after falling in the Miami final. “I'm playing well [enough] to fight for everything.”

With the clay-court season set to start next week, expect Nadal to be feeling even better about his tennis.

FedEx ATP Win/Loss Index (2017)

Player W-L
Roger Federer 19-1
Rafael Nadal
Jack Sock
Grigor Dimitrov  17-4 
Jo-Wilfried Tsonga  17-4 
David Goffin  17-7 
Dominic Thiem  17-8 

3. Nick Kyrgios' Play

His start to the year was hardly what he had imagined: a five-set loss to Andreas Seppi in the second round of his home Grand Slam. But Kyrgios has answered nearly every question that trailed him in Melbourne.

Mental toughness? See back-to-back straight-set wins against Novak Djokovic in Acapulco and Indian Wells. Showing up at every event? His last four tournaments: semi-final in Marseille; semi-final in Acapulco; quarter-final in Indian Wells; and semi-final in Miami.

His attitude? “I feel like my level of tennis, it's always been high, but mentally I'm competing for every point. That's making the difference,” he said after his Miami semi-final loss to Federer, one of the best matches of 2017. “I got a lot of work to do. I'm 16 in the world. There are 15 players better than me.”

4. Jack Sock Climbing The Emirates ATP Rankings

The Nebraska native has more than carried the American flag for the first three months of the season. After not winning a title during all of 2016, Sock has already captured two crowns – Auckland and Delray Beach. At the March Masters, he made his first Masters 1000 semi-final in Indian Wells (l. to Federer) and backed it up with a last-eight showing in Miami (l. to Nadal).

Sock is 18-4 on the season, second behind only Federer and Nadal in wins. The Kansas City resident reached a new career high of No. 15 in the Emirates ATP Rankings this week. At this rate, the 24 year old will crack the Top 10 by the end of the season and become the first American to do so since John Isner in May 2014. Sock is currently No. 7 in the Emirates ATP Race To London.

5. Alexander Zverev Leading #NextGenATP

#NextGenATP players continued to make strides during the first few months of 2017. Russian Daniil Medvedev celebrated his first final at the Aircel Chennai Open (l. to Bautista Agut). Emirates ATP Star Of Tomorrow Taylor Fritz checked off his first Top 10 win by beating Marin Cilic in Indian Wells. But no #NextGenATP player has delivered like Zverev this season.

The 19 year old won his second ATP World Tour title at the Open Sud de France in Montpellier. In Miami, he improved to 2-0 against Stan Wawrinka in their FedEx ATP Head2Head rivalry and made his first Masters 1000 quarter-final (l. to Kyrgios). The strong start has Zverev atop the Emirates ATP Race To Milan, which will determine who qualifies for the inaugural Next Gen ATP Finals, to be held 7-11 November in Milan.

6. Grigor Dimitrov Knocking On Top 10

The Bulgarian already has two titles – Brisbane and Sofia – and returned to the semi-finals of a Grand Slam for the first time since 2014 Wimbledon. Before falling to Nadal in the Australian Open semi-finals, Dimitrov had won 10 consecutive matches. He's 3-1 against Top 10 players and he might be rejoining that elite group soon.

Dimitrov is currently No. 12 in the Emirates ATP Rankings but he's played like a Top 5 player so far this season. His spot in the Emirates ATP Race To London: No. 4.

7. Surprise Beginnings From Andy Murray, Novak Djokovic

They're ahead of Federer in the Emirates ATP Rankings, but No. 1 Murray and No. 2 Djokovic have garnered a small fraction of the attention that Federer has received so far. Djokovic started the year with a memorable run in Doha, beating Murray for the title in one of the best matches of the year. That epic final had tennis fans thinking that this year's battle for No. 1 would again be a two-man affair.

But both Murray and Djokovic suffered early losses in Melbourne. Murray rebounded in Dubai to celebrate his 45th tour-level title, while Djokovic fell to Kyrgios in the Acapulco quarter-finals. In Indian Wells, both fell before the last eight, and they both withdrew from Miami with elbow injuries. With three Masters 1000 tournaments only weeks away, though, both men will be looking to get their season back on track.