Russian Andrey Rublev defeated Duckhee Lee 6-4, 3-6, 6-4 in a quarterfinal battle of NextGen teenage tennis stars at the Rennes Challenger Friday afternoon. The 19-year-old Rublev, who had knocked out top-seeded Jeremy Chardy in the first round on Wednesday, used his powerful serve and punishing ground game to wear down the pesky and tenacious Lee. Both players had competed at the Australian Open last week, where Rublev won four matches (three in the qualies) before losing to Andy Murray in the second round. Lee, an 18-year old from South Korea, lost in the third round of the qualies. This was the pairs first meeting. Rublev lost but six points on his serve in the opener, capturing the lone break of the set in the ninth game to take a 1-0 lead. Lee dialed in on Rublev’s serve in the second set as the Russian’s first service percentage fell off to 52 percent after a sparkling 64 percent in the first. The Korean broke in the fourth game for 3-1, saved a break point in the fifth, and forced three break-point opportunities on Rublev’s serve in the sixth before the Russian staved off going down two breaks. Lee held twice more to level the match at a set apiece. Rublev got his serve back on track in the third set, holding four times at love and yielding just three points. Lee saved four break points in the sixth game and two match points in the 10th, but Rublev prevailed by closing it out on the third match point after one hour 51 minutes of high-octane action. Rublev served 12 aces, won 85 percent of his first service points and saved six of seven break points. Lee won 74 percent of his first serves and erased seven of nine break points. Rublev will take on Blaz Kavcic of Slovenia in the semifinals tomorrow.