With more than a month to go until its official conclusion, the 2009 tennis season already has been one of the most memorable on record. Roger Federer completed the career Grand Slam in Paris, formerly the site of his annual undoing, and claimed a record-setting 15th major title with an epic Wimbledon victory. In stunning plot twists, Kim Clijsters won the U.S. Open in just her third tournament back from retirement, and Rafael Nadal, the four-time defending French Open champ, lost early at Roland Garros. And there was significant controversy as well: Dinara Safina’s extended tenure as world No. 1, despite her underwhelming performances at the Slams, and Serena Williams’ ferocious tirade at Flushing Meadows.

You may think that a letdown is inevitable in 2010. But three events in the past few weeks suggest that another fantastic year of tennis lies ahead of us.

1. Juan Martin del Potro defeats Roger Federer in the U.S. Open final
Since the summer of 2005, Federer and Nadal have had a nearly exclusive grasp of the Grand Slams – before this year’s U.S. Open, they had combined to win 17 of 18 majors. Del Potro’s five-set tour de force in Queens hardly puts the duopoly’s accomplishments in the rear-view mirror, but the upset was a giant step forward for those chasing tennis’ two titans. Never before had Federer or Nadal lost a Grand Slam final to anyone except…Federer or Nadal. Del Potro showed that it’s possible for another player to beat the Swiss in a major final (he also beat Nadal in the semis).

There’s no guarantee that del Potro’s breakthrough win signals the end of the Roger-Rafa hegemony – after Novak Djokovic won the Australian Open in 2008, Federer and Nadal went on to split the next six majors. But the landscape appears different this time around. The ATP’s Top 10 looks hungrier than it has in years, and a number of players, including the Argentine, made significant inroads in 2009. In his third All England Club final, Andy Roddick came as close as he’s ever come to winning Wimbledon. Despite underperforming in Melbourne and Flushing Meadows, Andy Murray rose to No. 2 in the world and made great strides on clay and grass. And Robin Soderling, who shocked Nadal at the French, proved that he’s more than just the answer to a trivia question; he’s developed into a consistent threat to the big guns.

Despite their progress, I wouldn’t label any of these players as a favorite to win the Australian Open (look where those expectations got Murray earlier this year), or any other Slam, until they’ve proven that they can sustain their level of play when it counts most. But I wouldn’t be surprised to see one of them collect a major at some point next season, even at Roger’s or Rafa’s expense. Murray, Roddick, Soderling and others will get their first chance in just a few months’ time.

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!Justine Henin

Henin says she's retooling her serve in preparation for her comeback in 2010. (Jasper Junien/Getty Images)2. Justine Henin announces that she’s returning to professional tennis**
For most of 2009, the talk surrounding the WTA centered on the endless debate of, “Who’s the true No. 1: Safina or Serena?” Thankfully, Clijsters and Henin, a pair of Belgians returning from sabbatical, shifted our focus onto something else. (And not a moment too soon, as Safina, still ranked No. 1, recently bombed out of yet another major in embarrassing fashion.) Even better, early indications suggest that their comebacks aren’t simply sentimental, but legitimate.

Clijsters’ remarkable title run in New York showed that she has plenty left in the tank; it’s logical to think that Henin, a seven-time major champion and still just 27, can also thrive in the current environment. Like Clijsters, Henin will look to dictate points with her potent and picturesque backhand. But Henin is looking to add a new shot to her classic arsenal – an improved serve. That’s a smart decision – players tend to rely on their serve more as they age, and with the lackluster serving currently on display in the women’s game, possessing a formidable first strike is a big advantage.

One might think that given Clijsters’ immediately successful comeback, the pressure’s also on Henin to prosper. But the diminutive Belgian is already an all-time great; she’s won every major except Wimbledon, the focus of her return. The pressure is still squarely on the usual Slam-less suspects: Safina, Elena Dementieva, Jelena Jankovic. A free-swinging, newly-motivated Henin? She should be fun to watch.

3. Switzerland and Spain are drawn to face each other in the first round of Davis Cup play
As with all things involving Federer and Davis Cup, it’s best to employ a wait-and-see approach. Although the world No. 1 has participated in Switzerland’s Davis Cup playoff matches in each of the past five years, he hasn’t played in a World Group tie since 2004. But should Federer elect to represent his country next March, the potential opening-round matchup is even more tantalizing than the Federer-Roddick rubber that never materialized this March: Federer-Nadal.

Still, even if Federer commits, it takes two to tango – and after Nadal’s injury-riddled season, first-round Davis Cup duty is no sure bet.

But if the stars align – and head to Spain – we'll have a new context in which to enjoy Roger v. Rafa. Federer and Nadal have met in almost every significant tennis competition, but never in Davis Cup. It would be fascinating to see these two, still in their primes, square off with national pride at stake. And don’t forget the all-important doubles rubber: It’s possible that we could see Roger and Rafa tangle on consecutive days.

First-round Davis Cup ties rarely capture the attention of American sports fans – for one, few of these contests are actually broadcast on television. But if Federer and Nadal come to play, Switzerland-Spain is must-see TV here in the States. I hope one of the networks agrees.

Ed McGrogan is an assistant editor for TENNIS.com.