The Big Four have dominated this generation, but who will own the next?

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The first Grand Slam tournament of 2017 is in the books. As usual, the Australian Open leaves us with a number of impressions -- and questions -- regarding the rest of the year and a fair amount of time to mull them over before the next major gets under way in May in Paris. Here are 10 takeaways from the tournament Down Under.

1. 2017 is shaping up as the most multi-dimensional year in men's tennis.

For just the second time in the past seven years, the biggest question leaving Melbourne isn't, will Novak Djokovic complete a calendar year Grand Slam? With Roger Federer and Rafael Nadal back in the mix, Djokovic chastened by yet another setback, and Murray apparently not quite ready to dominate, we very well could see four different winners at the majors. Hard to believe that just weeks ago, everyone expected a new year dedicated to a Djokovic-Murray rivalry and their battle for No. 1.

2. Serena Williams showed -- yet again -- that any reports of her demise or even her decline have been greatly exaggerated.

It wasn't so much that

Williams won this tournament again, securing the Open-era record with 23 major singles titles. It was how she won it. There were no overwrought demonstrations, no meltdowns, no patches of horrible play followed by desperate comebacks. She left all that behind on the road to No. 23 and that kills all those theories that age, better competition and a lifetime of pressure have finally brought her to the end of the road as a competitor. Williams had a challenging draw and she didn't drop a set. By the end of the tournament, she also had earned back her No. 1 ranking and, seemingly, an appetite to hunt down Margaret Court and her all-time Grand Slam title record of 24.

3. The faster surface speed produced better, more diverse tennis.

The relatively fast speed of the Plexicushion courts Down Under played a significant role in the sensational but never outlandish results we saw this year. Today's' typical slow hard courts, outdoor or indoor, provide an advantage to consistent, defense-minded players. Speed them up and you begin to reward the players who are willing to take more chances, attack and even serve-and-volley more frequently. That cohort includes flamboyant risk-takers like Mischa Zverev (who upset top seed Andy Murray) but also proven all-purpose veterans like Federer. Tennis simply benefits from the diversity.

4. Coco Vandeweghe has all the right stuff to flourish in today's WTA.

At 25, Vandeweghe could still emerge as a force in women's tennis and the much-longed-for successor to Serena and Venus Williams. She has a big serve and the obligatory booming groundstrokes, moves well at 6-foot-1 and has loads of bravado. Just as important, she just might spark a stronger flame in the young lady most people have tabbed as a successor to the Williamses, Madison Keys. Keys missed the tournament due to minor wrist surgery in the off-season, but you can bet that Keys took note of Vandeweghe's progress.

5. Rafael Nadal's hopes to add a 10th French Open title to his collection just went through the roof.

As bitter as the loss to Federer in the final must have tasted, Nadal's performance in Melbourne strongly suggested that he's found the confidence that was, somewhat mysteriously, absent for so long. That's great news for him because his superiority on clay has always been a marvel of our era. Remember, he destroyed two opponents last year at Roland Garros before his bad wrist forced him to quit before his third-round match. Nadal probably will load up his clay-court spring schedule in order to boost his ranking enough to secure a top four seeding in Paris.

6. Grigor Dimitrov may finally have figured it out.

Among all the also-rans in the men's draw, semifinalist Dimitrov was by far the most impressive. Once widely known as Baby Fed, his talent and tools for today's game have never been questioned. He rose as high as No. 8 in 2014, the year he made his much-heralded first and, as it turned out, only previous Grand Slam semifinal at Wimbledon. Then he became a sometimes boyfriend to the stars and an underachieving player. He started this year with a new coach, a restructured game and an honest grasp of his shortcomings, vowing that he's changed.

9. Novak Djokovic should do a career review.

The former No. 1 needs to think things through all over, from his scheduling to his coaching stable. Is it still a good idea to play no warm-up events before a Grand Slam? Was it a good idea to part ways with the coach who was with him through his most of productive period, Boris Becker? Things only seemed to get worse after they broke up at the end of last year. In Australia, Djokovic led wild card Dennis Istomin two sets to one in the second round but lost. Sure, Istomin played well, but still. The facts seem indisputable: Djokovic just hasn't been the same since he completed his career Grand Slam at the French Open.

8. Maria Sharapova will have her work cut out when she returns.

Sharapova, who has a career Grand Slam, once enjoyed a significant advantage in power over a great number of her opponents. But while she's only been out of the game for a year, the number of women who can match her power and have big-match experience has grown considerably. Consider Vandeweghe, who knocked out top-seed and No. 1 Angelique Kerber, a prime example. Then there's Keys, defending French Open champ Garbine Muguruza, Petra Kvitova, Karolina Pliskova, and Johanna Konta, a hard-nosed competitor who lost to Serena Williams in the Australian semis and won't be intimidated by anyone. All of them can match or surpass Sharapova's power.

7. American fans may have a lot to be excited about.

Or at least they will get to exercise their name-check skills. It appears as though the Williams sisters are giving the stable of promising young American players, led by Keys and Vandeweghe, another year to develop the skills to take over at or near the top. There might be a smooth transition in the works. Among the men, Jack Sock played two good matches before he ran afoul of Jo-Wilfried Tsonga on the fast Plexicushion that so suits the Frenchman's game. For the first time in more than a decade, there were seven men from the U.S. age 20 or younger in the Australian Open draw.

10. When it comes to American tennis, there's always the doubles.

Well, it may not be the sexy headline everyone weaned on the McEnroe-Connors or Sampras-Agassi years craves, but the reality is that the U.S. has a great doubles tradition and rich history. And, by the way, John McEnroe himself is a big part of it. Bob and Mike Bryan were trying for a record-tying 17th major doubles title in Australia, but fell just short, losing in the final to Henri Kontinen and John Peers.

Bethanie Mattek-Sands did better with her partner, Lucie Safarova, winning the women's doubles. It was Mattek-Sands' fourth Grand Slam women's doubles title (she also has a mixed title, with Mike Bryan). The win also leaves Mattek-Sands ranked No. 1 in the world in doubles. In addition, Abigail Spears joined with Colombian Juan Sebastian Cabal to win the mixed doubles.