BEIJING - Andy Murray stormed into the China Open quarter-finals with a 6-2, 6-1 victory over Andrey Kuznetsov on Wednesday, as on the outer courts the tournament's younger players appeared in control.

The 49th-ranked Russian broke Murray's serve in the first game, battling through four deuces to take the first point of the match.  The world number two dropped another serve in the first set, and one in the second, but otherwise allowed the 25-year-old little room as he closed out the match in 76 minutes.

The women's top seed Angelique Kerber booked her spot in the round of 16, beating Barbora Strycova in two sets, 6-3, 7-6 (7/4). "I was just trying to be more aggressive, so that was my plan, to just to go for it, and (to make) her run," Kerber said after the match.

The German two-time Grand Slam champion will meet 22-year-old Ukrainian Elina Svitolina, who downed Savine Lisicki 6-4, 6-4. Other members of the younger generation also took charge Wednesday.

Ninth-ranked 21-year-old Madison Keys dismissed two-time Grand Slam champion Svetlana Kuznetsova, 31, in two sets, 7-6 (7/2), 6-2. The American is targeting a spot in the final to qualify for the eight-player WTA Finals in Singapore for the first time, but will have to get through two-time Wimbledon champion Petra Kvitova in the quarter-finals.

Briton Johanna Konta is also still in the running to qualify for the season finale for the first time -- and possibly break into the top ten -- as she beat Timea Babos 7-5, 6-2. Twenty-one-year-old British qualifier Kyle Edmund outgunned 18th-ranked Roberto Bautista Agut 6-4, 4-6, 6-4 to set up a quarter final meet with Murray.

Meanwhile, German teenager Alexander Zverev beat American Jack Sock, who is five years his senior, 6-4, 6-2. He will face 13th-ranked veteran David Ferrer, 34, in the next round. Zverev claimed the scalp of world number 10 Dominic Thiem in the first round of the China Open, a week after he beat world number three Stan Wawrinka to claim his maiden career title in St Petersburg. Twenty-two-year-old Caroline Garcia crushed the home crowd's hopes as she ousted Peng Shuai, 30, after a tense three set tie break, 6-3, 3-6, 7-6 (7/4).

Nishikori pulls out of Japan Open: Top seed Kei Nishikori withdrew from the Japan Open Wednesday due to a buttock muscle injury, disappointing home fans hoping he could recapture the trophy.

The world number five became the latest star to pull out of the injury-plagued tournament, after US Open winner and defending champion Stan Wawrinka withdrew due to a back injury.

Nishikori retired during the first set of his second-round match against Joao Sousa of Portugal, ranked 34th in the world. Going into the match, Nishikori looked to be in solid shape, comfortably building a 3-0 lead as he made his rival run back and forth across the hard court at Ariake Colosseum.

But the 26-year-old requested a medical timeout, asking his trainer to massage the left side of his lower back. Resuming the match, Nishikori was clearly a different man, grimacing at times, although he managed to hold his service game to make it 4-0 before his legs gave up. Sousa quickly made it 4-3, and Nishikori was forced to withdraw 41 minutes into the match. The Japanese star, title winner in 2012 and 2014, voiced disbelief at the outcome. "Until a second ago, I was feeling really good and made it 3-0" before things deteriorated, he told a press conference after the match. I still cannot believe what happened." Sousa will now play against Belgian fifth-seed David Goffin, who defeated Jirí Veselý of the Czech Republic 6-3, 7-5. Fourth-seed Marin Cilic also defeated Spaniard Fernando Verdasco 4-6, 7-5, 7-5 in the second round.

Gilles Muller of Luxembourg advanced to the second round by defeating Czech third-seed Tomas Berdych, winning the first set in a tie break before dominating the second set to claim victory 7-6 (9/7), 6-1. Berdych also asked for a medical timeout in the second set, but stayed on to finish the match.