Here's a look at 10 questions to consider for the rest of the season following an action-packed two weeks at the Australian Open.
1. Where does Stanislas Wawrinka go from here?
It's not easy to tell, because the 28-year-old looks neither like a young gun announcing himself nor a veteran having a last hurrah. Perhaps, like him, it will be somewhere in between. Coming into the Australian Open, Wawrinka had reached the semifinals of both the past two big events -- the U.S. Open and the year-end Tour Finals. That meant his performance Down Under, though unexpected, wasn't such a huge leap.
And if he keeps playing the same way, the new No. 3 will be a contender for most of the other big titles this season. But there hasn't been much to suggest that he can do it week in and week out like Nadal or Djokovic have been doing, and that's the standard required to reach the top these days. There's also the possibility that the attention and expectation following this win could affect him, though he seems so level-headed that feels unlikely.
2. Is the Big Four no more?
They had won 34 of the past 35 Slams. Then Nadal's body buckled once more. Djokovic once again faltered in a tight Grand Slam match. Andy Murray has sunk to No. 6 following back surgery. Roger Federer is No. 8. Their collective dominance is clearly not what it once was.
Don't write the group off just yet, though. Even a subpar Nadal looked formidable for most of the two weeks, and he is expected to recover quickly. Djokovic was close to winning against Wawrinka. Murray is on the mend, and Federer looks better than he has in a year.
The question is whether Murray and Federer can climb back up alongside Nadal and Djokovic, or whether they will drop back into the rest of the pack. Also whether anyone else, like Wawrinka, can join them. If not, it will continue to be what it has actually been for the past year: Not the Big Four, but the Top Two and everyone else.
3. Who will be inspired by Wawrinka's win?
One of the most interesting things to watch will be whether any of the other contenders-in-waiting will be inspired by Wawrinka's win. Tomas Berdych, Juan Martin del Potro, Jo-Wilfried Tsonga, Richard Gasquet, Milos Raonic and Grigor Dimitrov among the younger set are all possibilities. At the very least, it should give them renewed belief after a discouraging few years of Big Four domination.
4. Will the injuries continue?
Injuries marred the Australian Open, most prominently affecting Nadal, Serena Williams, Maria Sharapova, Ana Ivanovic and, it now appears, Del Potro. Also, Murray and Sharapova had only just come back from problems that kept them out for much of the second half of last year. It continued what had already been a spate of injury retirements and withdrawals during the first two weeks of the season, a worrying sign so early during the year.
5. Can the WTA standouts build on their big results?
Plenty of players scored upsets in the women's draw -- among them Ivanovic against Serena Williams, Agnieszka Radwanska against Victoria Azarenka, Dominika Cibulkova against Sharapova, Flavia Pennetta against Angelique Kerber and Eugenie Bouchard against Ivanovic.
But Cibulkova was one of the very few who was able to follow hers up, defeating Simona Halep and Radwanska to make the final. For the others, especially those like Ivanovic who have been waiting a while to produce such performances, it will be important to show that they can play like this more consistently.
For Li Na, who dodged all the upheaval and won the tournament, her second Grand Slam win is an opportunity to try to establish herself as one of the tour leaders, and not just a perennial threat.
6. Can the young guns keep it up?
Veterans are in charge these days, but a few younger names did show progress at the Australian Open. Bouchard, 19, achieved a semifinal -- and stardom -- with her calm, collected performance. Dimitrov, 22, challenged Nadal in the quarterfinals. Garbine Muguruza, 20, made it to the second week. And Aussie teens Thanasi Kokkinakis and Nick Kyrgios both won matches and got locals excited for the years ahead.
Then again, last year the talked-about prospects were Sloane Stephens, Bernard Tomic and Milos Raonic, who all struggled for a while afterward. So the next task for this year's breakouts is to maintain their improvement following the tournament.
7. Who will be more successful, the legends or the established coaches?
Coming into the tournament, the big news was legends like Stefan Edberg and Boris Becker joining their contemporary Ivan Lendl as coaches. It's too early to tell how effective they will be, but at the Australian Open it was more established coaches who stood out.
Among them were Magnus Norman, once a top player himself and former coach of Robin Soderling who is now working with Wawrinka, Justine Henin's former coach Carlos Rodriguez, now working with Li Na, and Roger Rasheed, who has worked with Lleyton Hewitt, Jo-Wilfried Tsonga and Gael Monfils and recently took on Dimitrov.
8. Is net-rushing starting to come back?
Federer, now working with serve-and-volley legend Edberg, was trying to get to net more often. Wawrinka took his opportunities, as well. Djokovic, also working with a serve-and-volleyer in Becker, continues to work on it. Victoria Azarenka, trying to fend off Radwanska, was trying the play regularly. Guided by Rodriguez, Li is trying to incorporate serve and volley in her game.
Those were a few signs that the old-fashioned tactic may be making a comeback, but let's see if the early-season resolve lasts as things go on. It can shorten points and adds variety for viewers, but isn't easy to pull off against contemporary baseline games.
9. Which streaks will be broken next?
The Aussie Open was a tournament for turnarounds. Serena Williams and Djokovic had their 25- and 23-match win streaks broken. Wawrinka snapped an 0-12 head-to-head streak against Nadal and a 14-match losing streak to Djokovic. Ivanovic defeated Williams after four straight losses to Serena. Radwanska beat Azarenka after seven straight losses in the series, ending Azarenka's 18-match overall streak, as well.
The reversals may also have signaled a change in attitude. For a while, it seemed underdogs were too willing to go out, play their usual game and accept the usual result. Recently, more have been stepping up, taking chances and, occasionally, pulling off a big win.
It may have been Wawrinka who started it 12 months ago when he took things to Djokovic in their Australian Open match that year. This year, he capped it by taking the title. So when a player next goes out with a losing record against an opponent, don't count them out like before.
10. Will courts get faster?
The lead-up tournaments reportedly featured very fast courts, and some players felt that conditions at this year's Australian Open were a little faster than even last year's sped-up version. It follows a quickening of surfaces at some tournaments played after the U.S. Open last year.
That doesn't mean a concerted or coordinated effort is underway, but after so many years of players talking about conditions being slower, tournament officials may now be leaning toward making things faster once again. If that continues to happen, expect more shake-ups.