Wow, what a difference a year makes. And I mean WOW!

When Novak Djokovic lifted the trophy at last year's French Open, cementing his dominance with a fourth Grand Slam title in a row and 12th overall, the future seemed, well, more of same.

In the final, Djokovic beat his main rival, Andy Murray, who was solidly entrenched as world No. 2. The brightness of the Roger Federer–Rafael Nadal era had faded. Neither had won a major since 2014 and injuries had kept Federer out of Roland Garros and Nadal retiring in the third round.

On the women's side, Serena Williams was surprised in the final by up-and-comer Spaniard Garbine Muguruza, but everyone knew Serena would be back to fight another day in her quest to surpass Margaret Court's record 24 major titles. In fact, Williams got back on track quickly, winning Wimbledon and then the Australian Open early this year to pull within one major of Court.

But then came an announcement this spring that no was expecting, that Serena was expecting the birth of her first child in September with fiancé Alexis Ohanian, co-founder of the social website Reddit. Williams plans to return to the tour next year, reminding parents everywhere that a baby tends to change one's life … just a bit.

Back to Djokovic. He left Paris last year justifiably eyeing Federer's record of 17 major titles. And why not? The Serb was at the top of his game, fit as a fiddle, and just 29 years old — surely he had five or six more majors in him. And Federer? Nearing 35 years old, he wasn't going to be adding to his Grand Slam total.

Other players would consider two tour titles and a U.S. Open final over the next 12 months to be an excellent stretch. But not when you're Novak Djokovic. He might still be No. 2 in the world, but that belies tepid results and turmoil churning within. Is it the unspecified personal problems he cited last summer, a loss of work ethic referenced by departed coach Boris Becker, or perhaps the entrance into his life of a man being called his "spiritual guru"? Whatever the problem, Djokovic has one, leading him to fire his entire team earlier this month and hire Hall of Famer Andre Agassi to coach him in Paris, a man with plenty of experience climbing out of his own career valleys.

If misery loves company, then that may partly explain why Murray has played nothing like his top ranking this year either, suffering several early-round losses and entering Paris with questionable prospects.

Which brings us back to the opening line of this column and those two washed up stars, Federer and Nadal. It not only shocked the tennis world when they unexpectedly faced each other in the final of the Australian Open, but perhaps even settled the Greatest Ever debate when the Swiss won a five-set thriller. It truly was, in Millennial-speak, "epic."

And it wasn't a one-off. Both are healthy again and mowing down the competition. After tallying his 18th major, Federer won back-to-back titles in Indian Wells and Key Biscayne. And then Nadal stepped onto his beloved clay courts this spring and dominated, winning back-to-back-to-back in Monte Carlo, Barcelona and Madrid. Only fatigue stopped him at the Italian Open in Rome.

Before you set your DVR to record a Federer–Nadal final, though, you should know that Roger is skipping the clay court season to rest for Wimbledon and the U.S. Open, where he surmises the faster courts give him a better chance of going all the way. That leaves the resurgent Nadal, now world No. 4 and boosted by new coach and former Roland Garros champ, Carlos Moya, as the favorite to win his 10th French. Stan Wawrinka, the 2015 winner, or one of the young guns such as Austrian Dominic Thiem or German Alexander Zverev could get in Nadal's way, but don't count on it.

So with Serena out, who will win the women's title? World No. 1 German Angelique Kerber and defending champ Muguruza have followed Djokovic's and Murray's lackluster form this year. Two-time winner Maria Sharapova just returned from a 15-month suspension for using a banned substance and was denied a wild-card entry by tournament organizers. Other multiple Grand Slam champions such as Victoria Azarenka and Petra Kvitova are either out or likely won't be a factor — the former is on maternity leave while the latter is returning for her first tournament since — get ready for this — having her playing hand slashed by a home invader this past December.

Truly, much can happen in a year … and will over the next two weeks in Paris. We knew the world is a turbulent and unpredictable place. And now we know the same about the professional tennis tour.

Minnesota's David Wheaton best result at the French Open was the third round in singles and semifinals in doubles. His most recent book, "My Boy, Ben," has received widespread coverage and commendation. Find out more at DavidWheaton.com.