Serena Williams 'chills out' to clinch Charleston treble

(CNN) -- Defending champion Serena Williams edged towards another milestone with the 49th WTA Tour title of her career on Sunday, coming from behind to beat Jelena Jankovic in the final of the Family Circle Cup in South Carolina.

The world No. 1, who is seeking to become only the 10th woman to have reached a half-century, triumphed for the third time on the green clay at Charleston as she won 12 of the last 14 games.

The American, who had a similar run in vanquishing Maria Sharapova to claim a record sixth Miami title last weekend, posted a 3-6 6-0 6-2 victory in just under two hours.

Jankovic, herself former top-ranked player but 18th going into this event, had hopes she might repeat her 2008 Rome win on red clay over Williams as she won a 45-minute opening set.

But, after an argument over the Serbian apparently trying to take her serve too quickly, the 15-time grand slam champion stepped up a gear to control the match.

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"I felt so close in that first set. I felt like I could have been up 3-0,"said Williams, the only woman to have won more than $40 million in prize money.

"She was playing really, really well, but it was just a shot here, a shot there, and she played really well in the big points. And I had so many opportunities that I missed. She took advantage of that, and she went on to glory in that first set.

"After that I just got really relaxed and was like, 'Serena, you have to chill out and not get crazy and if you win, great. If not, you're trying. Just do the best you can.' "

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She won despite double-faulting on her first match point and hitting the net with a forehand on her second, but still managed 27 winners against 13 unforced errors in those last two sets, having been 12-123 in the first.

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The 31-year-old, who beat older sister Venus in Saturday's semifinals, took her career record to Jankovic to 6-4 and extended her record to 75-4 since the start of the 2012 clay season a year ago.

Jankovic had won 14 of her last 16 matches, reaching the semis in Miami and winning the 13th title of her career in Colombia.

"I thought I played pretty well in that first set -- I was holding my serve and then waiting for my chance to break," Jankovic said.

"In the second set I had 40-15 in that first game and then again in another couple of games I had 40-15, 40-0. I should have focused and gotten those games."

Meanwhile, the Czech Republic became the first team through to the semifinals of the men's Davis Cup competition on Sunday, completing a 3-1 win over Kazakhstan in Astana.

Lukas Rosol won 7-6 (7-5) 6-7 (2-7) 7-6 (7-5) 6-2 over Evgeny Korolev to earn a home clash with Argentina in September.

It also put the defending champions top of the ITF nation rankings, ending Spain's four-year reign.

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Argentina went through with a 3-2 win at home to France, as world No. 71 Carlos Berlocq upset 13th-ranked Gilles Simon 6-4 5-7 6-4 6-4 in the decisive rubber.

World No. 8 Jo Wilfried-Tsonga had leveled the tie by earlier beating Juan Monaco 6-3 6-3 6-0.

In the other quarterfinals, Serbia won 3-1 against the United States as world No. 1 Novak Djokovic battled to a 7-5 6-7 (4-7) 6-1 6-0 victory over Sam Querrey in Idaho.

Djokovic suffered an injury scare when he twisted his ankle in the third game of the match, but was able to continue with painkillers while the usually strong-serving Querrey struggled with his own shoulder problem.

The Serbs took a 2-1 lead in Saturday's epic doubles rubber, as Ilija Bozoljac and Nenad Zimonjic defeated top-ranked Bob and Mike Bryan 7-6 (7-5) 7-6 (7-1) 5-7 4-6 15-13 in a match lasting almost four and a half hours.

Serbia, the 2010 champions, will next face Canada or Italy. That quarterfinal was 2-1 in the home team's favor after Saturday's doubles in Vancouver.