• Women: Serena Williams. The best by a healthy margin. She won 11 major singles titles -- including titles at the Australian Open and Wimbledon. And she played as well in 2009 as she did in 1999, the year she first broke through. Bonus points for her excellence in doubles, her success at the Olympics and her unrivaled competitive fire. The critics -- the "Hatorade drinkers," as she might put it -- will point to her selective scheduling, mysterious absences and penchant for drama. But maybe that helped inform her success.
Click here for Jon Wertheim's top male and top 10 female players of the decade
• Men: Rafael Nadal vs. Roger Federer, 2008 Wimbledon final. The match had it all: context, gravitas, swings in momentum, injury, recovery, sportsmanship, acts of God. And some of the highest quality tennis ever played. In the end, it was a five-hour infomercial for everything right and virtuous about the sport. Nadal ended up prevailing 6-4, 6-4, 6-7 (5), 6-7 (8), 9-7, but those prone to cliché had it right: Tennis was the real winner that day.
• Justine Henin vs. Jennifer Capriati, 2003 U.S. Open semifinal. A memorable contrast of styles (aesthetic, personal, physical, emotional), heavy-hitting tennis, a partisan crowd and a third-set tiebreaker. Henin was so depleted after her 4-6, 7-5, 7-6 (4) victory that she needed an intravenous drip afterward. Not that it stopped her from beating Kim Clijsters in the final the following night.
• Men: Fed's trickery. Leave it to Federer to elevate the between-the-legs shot from a fugue of showmanship to a bona fide weapon.
• Women: Venus serving at 129 mph. You want progress? This was twice as fast as some top players were serving just a generation earlier.
• Men: Relentless globalization. There is only one American currently in the ATP's top 10. Just as there is one Brit, Frenchman and Argentine. Spain, with Nadal and Fernando Verdasco, is the only country with multiple players in the top 10. The days of national powerhouses are over. The sport's ability to adjust to this reality will go a long way in determining its future success.
• Women: Sister dominance. Imagine if Tiger Woods had a brother, Lion, whom he battled for supremacy. The Venus and Serena Williams narrative has been well told, but it's still among the most underrated stories in sports. To repeat: Two sisters, who grew up in Compton, Calif., spent most of the decade batting the biggest titles back and forth.
• Men: Robin Soderling over Nadal, 2009 French Open fourth round. That Nadal lost at Roland Garros for the first time was upset enough. That, as the four-time defending champ, he lost to Soderling -- a modest clay-courter ranked outside the top 20 at the time -- was an all-time shocker. This result laid bare just how competitive men's tennis has become. It also gave some context to Federer's streak of 22 Grand Slam semifinal appearances.
• Women:Jill Craybas over Serena Williams, 2005 Wimbledon third round.The 30-year-old Craybas, ranked No. 85, a first-round loser in 17 of 24 Grand Slams she had played and owner of zero career victories against top 10 players, stunned an out-of-form Serena in straight sets. Craybas faced Venus in the next round and won two games.
• Men: Andy Roddick. No, really. Andy Roddick. He was blessed with an elephant gun of a serve, a potent forehand and ... not much else. He's gone to extreme measures to improve, wringing everything from his game, bouncing back from demoralizing losses and remaining in the top echelon for most of the decade. Plenty of players endowed with much more have done much less.
• Women:Justine Henin. In an age when a "Big Babe physique" (attribution: Mary Carillo) became a virtual prerequisite for success in the women's game, up stepped Henin, who's only 5-6 but walks among giants. Funny thing is, she sure doesn't get outhit much.
• Men: Mark Philippoussis.Marat Safin gets a pass with his two major titles. So we'll go with Philippoussis, a talented and physically hulking Australian, who squandered his gifts and his money in equal measure.
• Women: WTA leadership. The obvious choice is Anna Kournikova, who made millions but -- all together now -- never won a singles title. But what about the WTA corporate leaders in the early 2000s, who were unable to monetize a rich and diverse cast of players, in flush economic times no less?
• Men: Federer vs. Nadal. Just as "styles make fights" in boxing, the same goes for tennis. Federer-Nadal encompasses No. 1 vs. No. 2; righty vs. lefty; grace vs. power; elegance vs. grit. About the only thing missing is personal animus. On the other hand, this is the rare sports rivalry for which rooting for both sides seems perfectly reasonable.
• Women: Williams family vs. tennis establishment. From the day they burst on the scene, everything about them resisted convention. So it wasn't surprising that Venus and Serena Williams -- and their antagonistic father -- were frequently in the crosshairs. With a theme of race seldom far from the surface, there were feuds with other players, allegations of fixed matches, tournaments boycotts, accusations of faked injuries, disputes with televisions personalities, lawsuits and boos. But to the extent that the Williams sisters brought an "us against them" mentality to the sport, "us" tended to fare pretty well.
• Men:Gaston Gaudio (who?), Albert Costa (huh?) and Thomas Johansson (wha?) each won a major. But the vote here goes to ISL, the Swiss media and marketing company that pledged more than $1 billion to package men's tennis, only to collapse under the weight of its debt.
• Women:Ana Ivanovic. She not only won the 2008 French Open but also was hailed as the WTA's new transcendent star. Since then, she's been falling like the Las Vegas housing market. Here's hoping a second hit comes soon.
• Men:Guillermo Coria unravels. Coriawas cruising in the 2004 French Open final, on his way to his first Grand Slam title. With the Argentine two games from winning after dropping only three games in the first two sets, the notoriously restless Parisian crowd performed "the wave" and cheered raucously for Gaudio to come back. After that, the deluge. Coria lost the game, the set and eventually the match. And he was never again the same player.
• Women:Serena loses it. It was deep in the second set of her semifinal match against Kim Clijsters, the de facto final of the 2009 U.S. Open. Serena served and as the ball alighted, a call of "foot fault" pierced the air. Foot fault? The result was a vile and dramatic eruption that cost Serena the match and thousands of dollars in fines. Plus immeasurably more in goodwill.
• Men: Surprise doubles pairing. With no fanfare and no press releases, Amir Hadad and Aisam Qureshi, two journeymen unknown even to hardcore fans, teamed together in the 2002 Wimbledon doubles draw. No big deal. Except that Hadad and Qureshi represent two countries -- Israel and Pakistan, respectively -- that seldom teamed together. Despite protest, pressure and a threat by the Pakistani federation, they played on. (Later, Qureshi would also team with Rohan Bopanna, an Indian player.) It was a small step, but a step nonetheless.
• Women: Martina's comeback. The term "retirement" has become synonymous with "temporary leave" in today's WTA, a brief respite for burned-out twentysomethings. But after a six-year absence, Martina Navratilova returned to tennis in 2000 at age 44. She was a doubles specialist this time around, but it was no dilettantism. Playing with and against colleagues decades younger, she more than held her own, winning trophies and touring the globe. In 2006, weeks from her 50th birthday, she teamed with Bob Bryan to win the mixed doubles title at the U.S. Open.
• Men: Bob and Mike Bryan. Identical twins from California won more than 50 titles in the decade. Maybe because most foes still can't tell them apart.
• Women: Venus and Serena Williams. Other teams might be ranked higher, starting with Liezel Huber/Cara Black and Paola Suarez/Virginia Ruano Pascual. But when the sisters enter the draw, everyone else is playing for second place.
• Men: Goran Ivanisevic. He got only one trophy when he won Wimbledon in 2002, but claims it was his three personalities -- "Good Goran, Bad Goran, Crazy Goran" -- that enabled him to win. That and watching Teletubbies for inspiration. Not the slick packaging agents would advise, but this eccentricity was the main reason he endeared himself to so many.
• Women:Anna Kournikova. The relationship between an athlete's talent and popularity is not always symmetrical. We know that. But Kournikova took this reality to new extremes, becoming an A-list global celebrity without winning much.
• Men: Federer. Like an uncooperative boxing champ, Federer needs to be stripped of his belt.
• Women:Martina Hingis. The Adidas shirt with one long sleeve and one short sleeve (popularized, or unpopularized, by Hingis) beat out Serena Williams' catsuit. Which is saying something.
• Told that one could be arrested in the UK for having Rick Astley on your iPod, Roddick responded, "But you can get arrested in my country for lying under oath."
• The question to Andre Agassi: "If you could be a Jeopardy! answer, what would the question be?" Agassi responded, "This person hates annoying questions."
• James Blake, on the incessant griping of Chilean Davis Cup coach Hans Gildermeister: "I've had girlfriends that complained a lot but he took it to a whole new level."
• Asked to compare Wimbledon to the U.S. Open, Svetlana Kuznetsova remarked: "It's completely like black and blue maybe, or white and black, you know, or red and black, whatever, you know. It's just different. It's like Sprite and Coke, you know. Doesn't matter that I love Sprite more than Coke, but it's just completely different. But also I would love to do well here."
Let's finish with a few one-answer categories ...
Match-fixing scandal. No small feat this past decade, tennis steered mercifully clear of major performance-enhancing drug controversies. The sport did, however, endure a match-fixing scandal that was never resolved with real satisfaction. And the persistent problems that attend Internet gambling in an individual sport will continue to dog tennis going forward.
Players vs. tournaments. There have been occasional personality clashes, usually involving Lleyton Hewitt. Plenty of doubles teams divorced bitterly, Leander Paes and Mahesh Bhupathi among them. But the real significant split is between the players and the tournaments. "Labor" wants more money and more freedom. "Management" wants more commitments while keeping costs down. That the WTA and ATP tours represent both of these (inherently adverse) interests is the source of most of tennis' problems.
The perception problem. Tennis is boring, a carnival of aces with nothing resembling nuance. Federer has less personality than his racket. The players are coddled children of privilege. None of the above, of course, coincides with truth. But at some point perception hardened and the sport still contends with a serious image problem, no matter how inaccurate the image might be. The villain? Both lazy mainstream media and tennis' fragmented structure, which impedes meaningful p.r. and marketing.
Hawk-Eye. Replay technology has managed to advance the sport, enhance the quality of officiating and add entertainment for the fans. If only this could encourage tennis administrators to embrace change and technology more lustily.
On-court coaching. The ATP's short-lived dalliance with the round-robin format was a failure, but at least someone had the good sense to cut bait. Not so the WTA, which stubbornly refuses to admit that on-court coaching during matches has been a disaster.