WASHINGTON (AFP) - India's Somdev Devvarman took the greatest victory of his life by shocking sixth seed Marin Cilic while defending champion Juan Martin Del Potro struggled to advance Tuesday at the Washington Classic. Devvarman avenged a Chennai finals loss to Cilic by upsetting the Croatian sixth seed 7-5, 6-4 to reach the third round of the 1.4 million-dollar ATP hardcourt tournament, calling it the greatest triumph of his career. The 24-year-old qualifier, ranked 153rd, hit 62 percent of his first serves and saved 5-of-7 break points to eliminate 15th-ranked Cilic, who in January denied Devvarman a title in his hometown and in his first ATP title match. "All along I played well," Devvarman said. "My game plan was to compete as hard as possible and let the chips fall where they will. I took my chances well. I'm proud of the result." Taiwan's 62nd-ranked Lu Yen-Hsun made an upset bid of his own but fell short as second seed and world number six Del Potro of Argentina rallied for a 4-6, 6-3, 6-2 victory. "It was a difficult match," Del Potro said. "It took some time to find my rhythm." Lu broke in the seventh game of the first set and held through to take the set, but surrendered a break in the penultimate game of the second set and another to open the third. Sixth-ranked Del Potro broke again for a 5-2 lead and held again to reach a third-round match against Australia's Lleyton Hewitt or Israel's Dudi Sela. "Lu is a good player and he played a good first set," Del Potro said. "I was able to turn it around in the second set and take control in the third. I'm glad to be through to the third round." Devvarman, a two-time US college national champion at nearby University of Virginia, evoked loud support in improving to 9-10 in ATP matches, 7-2 in 2009. Reflecting on the achievement was not something Devvarman was willing to do while still fighting for a title. "I've put in a lot of work. I'm doing things the right way," Devvarman said. "I'll take a deep breath when I have some breathing space." Devvarman, who finally has a day off after four matches in as many days, will next face 33rd-ranked Croatian super server Ivo Karlovic or Germany's Rainer Schuettler. Devvarman beat Karlovic in his run to the Chennai final. US top seed Andy Roddick, in his first event since losing an epic Wimbledon final to Roger Federer, could await Devvarman in the quarter-finals of the 1.4 million-dollar hardcourt event. "Andy who?" joked Devvarman. "I'm aware of where I am but I have to take it one match at a time." Germany's Benjamin Becker fired 27 aces to beat American Robby Ginepri 7-6 (7/3), 6-7 (1/7), 7-6 (7/4) and book a second-round match with Roddick, a three-time Washington champion who had an opening bye. "He had a big break and a good run at Wimbledon," Becker said. "It's his first match on hardcourts but you have to think he's going to play well. These conditions, with his serve, it's going to be tough to get a read on it. "I'm just going to have fun with it and see if I can do some damage." Former world number one Juan Carlos Ferrero of Spain beat Ecuador's Nicolas Lapentti 6-4, 6-7 (5/7), 6-0 to reach the second round just two days after losing to Russia's Nikolay Davydenko in a clay final at Umag, Croatia. "I was tired. It has been very difficult to recover well," Ferrero said. "After a month on clay it was difficult to play a match like this." Ferrero, the 2003 French Open winner, snapped a five-year title drought in April at Casablanca and won the last match to give Spain a 3-2 Davis Cup quarter-final win over Germany last month. "I'm motivated," Ferrero said. "I've returned to the same level as before."