Doubles partnerships, like many relationships in the real world, rarely last. Tandems drift apart, burn out, and look for a better fit. “Breakups” stem from monetary, personality and chemistry issues. Partnerships that endure the never-ending game of musical chairs usually do so because of success. Winning can smooth over everything.

In other words, it is not unusual to see players form new alliances. But when they are at the top of the tennis heap? This sparks curiosity. At least mine. Which is why I was interested in the recent split of Cara Black and Liezel Huber, who finished 2009 as the world’s top-ranked team and have won four majors together. Huber, 33, and Black, 31, parted ways after a first-round exit at the Sony Ericsson Open.

I received firsthand accounts of the disintegration in Paris, and it wasn’t pretty. According to Black, Huber dumped her because she wasn’t carrying her weight. “After Miami, she just felt like I wasn’t good enough to play with anymore,” says Black, who lost in the French Open’s fourth round with partner Elena Vesnina of Russia. Black—part of the illustrious Zimbabwean clan that also includes Wayne and Byron—went on to say she was blindsided by Huber’s decision. “She didn’t feel I was committed,” says Black, one of the fittest players on tour. “That’s just her opinion,” added Black, who wanted to take the high road but was clearly smarting. “If I don’t feel like I have the support of my partner, it’s no use playing. It’s time to move on and feel happy out there and have fun with whoever you’re out there with.”

Huber’s initial response to my inquiry was “I’m almost speechless,” but she was anything but. “I totally did initiate it,” she explained. “I wasn’t happy how we were going as a team. Tiger Woods changed his swing after he won the majors. I said to Cara, and these are the words: ‘We are like a 2002 Lexus. We are OK. But you know, 2003 is better, 2004 is better. We are competing against 2010 models.’” Considering their lofty place in the rankings, it was a tough call. “The easiest [decision] would have been just to go on,” she said.

Huber described how they hugged after the break in March and planned to reunite at some point, but she was surprised that a couple of text messages she sent to Black went unanswered. “This was an amicable split but it’s turned out way different than I expected,” said the USA’s Huber, who was born in South Africa.

Huber then ripped Black’s play, her practice habits and her self-absorption with the No. 1 ranking. “Cara had a terrible match in China,” she said of the pair’s quarterfinal loss in Beijing to Alisa Kleybanova and Francesca Schiavone. “She just tightened up completely. Whenever we mentioned something about the No. 1 ranking Cara would just tighten up. For me it was never ‘Liezel Huber the No. 1 player.’ But I felt for her it was ‘Cara Black the No. 1 player’….Who cares what the ranking is? That’s kind of the struggle that went on in the team.”

Huber said Black’s play deteriorated as the 2010 season went on. “We started losing more matches to more teams,” she says. “Indian Wells [another quarterfinal loss] was a shocker. Miami was even worse. We were up two breaks in the second set and Cara was serving and she served three double faults in that game. She got her confidence winded for the match. I always brought my best game to the court. She didn’t have her game.”

Huber, in the French Open semifinals with Spain’s Anabel Medina Garrigues, denied directly saying that Black’s skills were not up to par. She offered this retort. “If you feel that way, maybe there is truth to it,” she said. “Somehow when we were up in matches she choked on her serve, and that became a thing.”

Huber, who travels with a coach full-time, also criticized Black for using her husband, fitness expert Brett Stephens, as a tennis coach. Instead of addressing her on-court problems, Huber said Black just wished them away. “There is deliberate practice and just practice,” groused Huber. “I don’t think she had deliberate practice because she didn’t have a coach on hand to say, ‘Let’s work on this, work on that.’ She wanted her husband to be her coach and his expertise is not tennis.”

Relations have grown icier since. A Facebook posting by Huber’s coach, Roger Anderson, apparently led to a serious of misunderstandings and one confrontation. The two now barely acknowledge each other, according to Huber. “They don’t even greet me,” she said of locker room snubs in Stuttgart and Rome. “There is no common courtesy. I have common courtesy. I speak to everyone. Sometimes I speak too much but I prefer it that way.”

I wondered if their lack of success against the Williams sisters had played into the decision to split. In three Grand Slam meetings during the last year—including finals at the U.S. Open and Australian Open—the two failed to win a set. Both insisted it played no role. “They are not even a factor because the Williams sisters are the best,” said Huber. “We were losing to teams like—I‘m not going to say names because it’s embarrassing.”

It’s not the first time these two have had a row. They had a nasty breakup in 2005 (after winning Wimbledon no less) but mended bridges and started playing together again in 2007. Championships at the 2007 Australian Open, 2007 Wimbledon and 2008 U.S. Open followed. This time, the pair that still shares a website say the bridge is likely permanently damaged. “It’s up to her,” sniffed Black. “If she wants to play with me, we’ll see. It wasn’t my decision to stop. It was hers. Like I said, I’m not going to force any situation.”

“We left on good terms in Miami and I don’t know where it went wrong,” grumbled Huber. “The character that I’ve been shown is not a character that I like. Unfortunately, I don’t see where we can make a mend on this…I don’t want to spend my time trying to figure it out when they know what I stand for and what kind of person I am.”

Huber, still ranked No. 1 in doubles individually, said she had hoped to be back playing with No. 4 Black by now and even asked her about playing for the upcoming grass-court swing. She says she was “totally blown off,” which doesn’t sound far-fetched, even if the request does. “We don’t have the same goals,” she said. “I don’t want to hang on to No. 1.”

Despite their veteran status, both have some good miles left in their legs. They have been ranked No. 1 a combined 294 weeks and stand in second and third place all-time. What they will do about the WTA tour’s year-end championships is anyone’s guess. As a team they are second in the points race and could conceivably qualify for Doha with a few more tournaments together. That doesn’t seem to be in the cards. Since March, they have played with various partners. At Wimbledon, Black is planning to play with Daniela Hantuchova. Huber will partner with Fed Cup teammate Bethanie Mattek-Sands and then hinted she would play with retired Lindsay Davenport this summer. Both say they are looking for a more permanent situation. “I’ll see if I can find the right person and hopefully it’ll come together,” Black says. “I’m keeping my options open,” Huber says. Even success, it seems, can’t keep a team together.