Bethanie Mattek-Sands of the U.S. celebrates defeating China's Li Na in their second round match at the French Open tennis tournament, at Roland Garros stadium in Paris, Thursday, May 30, 2013. Mattek-Sands won in three sets 6-1, 5-7, 6-4. Serbia's Novak Djokovic mimics pushing the rain clouds away shortly before defeating Argentina's Guido Pella during their second round match of the French Open tennis tournament at the Roland Garros stadium Thursday, May 30, 2013 in Paris. Djokovic won 6-2, 6-0, 6-2. El serbio Novak Djokovic devuelve una pelota contra el argentino Guido Pella en la segunda ronda del Abierto de Francia el jueves, 30 de mayo de 2013, en París. China's Li Na serves the ball to Bethanie Mattek-Sands, of the U.S, during their second round match of the French Open tennis tournament at the Roland Garros stadium Thursday, May 30, 2013 in Paris. Russia's Maria Sharapova returns against Canada's Eugenie Bouchard in their second round match at the French Open tennis tournament, at Roland Garros stadium in Paris, Thursday, May 30, 2013. PARIS (AP) - Bethanie Mattek-Sands skipped backward across the clay, her wagging tongue framed by a smile as she savored yet another surprising victory for American tennis at the French Open. Rejuvenated by a rain delay, Mattek-Sands rallied past 2011 champion Li Na 5-7, 6-3, 6-2 Thursday in the second round at Roland Garros. Following the second interruption of the match, Mattek-Sands swept seven consecutive games from Li to take a 5-0 lead in the final set. She served out the victory with the sun shining as rain fell. "She's a champion, and I had to play some of my best tennis ever to beat her," Mattek-Sands said. I'm really proud of myself that I was able to close out the match the way I did. In men's play, six-time major champion Novak Djokovic gestured at threatening clouds between points, trying to keep them away, and managed to finish his drubbing of Guido Pella, 6-2, 6-0, 6-2. With five more victories Djokovic would become the eighth man to complete a career Grand Slam. 3 Victoria Azarenka, the Australian Open champion each of the past two years, beat Annika Beck 6-4, 6-3. Mattek-Sands was one of five U.S. women to reach the third round. Joining her Thursday were No. 54-ranked Jamie Hampton, who matched her best Grand Slam showing by beating Anna Karolina Schmiedlova 7-5, 6-2, and No. 17 Sloane Stephens, who defeated fellow American Vania King 6-1, 6-3. Melanie Oudin of the United States lost to Zheng Jie 6-3, 6-1. Ten singles matches were postponed, including seven-time champion Rafael Nadal against Martin Klizan, and the all-American encounter between John Isner and Ryan Harrison. Defending champion Maria Sharapova led 19-year-old Eugenie Bouchard 6-2, 4-2 when their match was interrupted by rain shortly before dark and suspended until Friday. Mattek-Sands matched her best effort at Roland Garros by reaching the round of 32. She failed to qualify for the Australian Open in January and arrived in Paris with a modest 10-8 record this year and a No. 67 ranking. "I was a little bit surprised today the way she's hitting," Li said. Well done for her. Li was ranked sixth. Since winning her lone major title, she has lost in the first or second round at four of the eight major events. Mattek-Sands' best Grand Slam showing came at Wimbledon back in 2008, when she reached the fourth round. The 28-year-old Minnesota native is better known for her loud outfits, such as the one she wore at the finish against Li - a long-sleeve top over a neon tank, a black skirt, black sneakers and - as the piece de resistance - black knee-high socks. "I haven't worn anything too crazy on court for a few years now," Mattek-Sands said. I feel like my racket has been doing a lot of the talking. Playing on cozy court 1, nicknamed the bullring, she appeared on the verge of defeat in the second set when rain prompted a 90-minute delay. She returned whacking winners, including a picturesque crosscourt backhand lob that gave her a break point and control of the final set. The 20-year-old Stephens also endured two rain delays and said she's still learning how to handle the waiting. "You literally have nothing to do," she said. Should I eat? Do cartwheels? You have no idea what to do, so it's just kind of you're lost. Last week in Brussels I got my nails done. And then we had chocolate and I watched my mom get makeup. And then I played a match. Despite the interruptions, Stephens overpowered King from start to finish and enjoyed a 26-1 advantage in baseline winners. Meanwhile, Oudin was doomed by a weak serve. She won only 19 of 51 service points and holding just once. 1 Jelena Jankovic won 12 consecutive games to beat the rain and Garbine Muguruza. Jankovic fell behind early but rallied past Muguruza 6-3, 6-0 shortly before showers interrupted the first matches of the day on 12 other courts. A brief dry spell allowed 2010 runner-up Sam Stosur to complete a second-round victory over Kristina Mladenovic 6-4, 6-3, before the rain resumed. With temperatures in the mid-50s, Jankovic took the court wearing pink leggings and a long-sleeve pink shirt. She looked uncomfortable at the start, losing the first three games, then won the rest after adjusting to the strokes of Muguruza, a 19-year-old Spaniard. "She's a great up and coming player," Jankovic said. She hits the ball very hard, very flat. And especially in the beginning of the match she gave me a lot of trouble. I figured out the way to play against her, and I think I did pretty well. Jankovic won with steady play from the baseline, while the big-swinging Muguruza committed 29 unforced errors. Jankovic, seeded 18th, is a three-time semifinalist at Roland Garros. She'll next play 2011 U.S. Open champion Stosur.