Spanish top seed Rafa Nadal overcame stubborn second-set resistance from compatriot Tommy Robredo to reach the Shanghai Masters quarter-finals 6-1, 6-4 on Thursday.
Second seed Novak Djokovic again looked impressive as he continued his imperious form in China with a 6-4, 6-2 thrashing of German qualifier Rainer Schuettler.
As the debate about the draining effects of the long men's season continued with Stanislas Wawrinka and Gael Monfils becoming the sixth and seventh players to retire injured from the $3.24 million tournament.
World number two Nadal, still not back at his best after an injury-disrupted second half of the season, cantered through the first set but lost his serve at the start of the second.
The 23-year-old Australian Open champion is nothing if not a fighter, however, and he battled back into the set in a marathon third game before breaking again for a 5-4 lead and serving out for victory.
Djokovic, who will move up to number three in the world next week, proved in winning the season-ending Masters Cup here last year that he has the legs to outlast his rivals.
The Serbian won the China Open title last weekend and his victory over Schuettler, which set up a tie against Gilles Simon, was his ninth in a row on Chinese soil.
"It was comfortable," the 22-year-old said. "I didn't play the last couple of games of the first set that well, but the important thing is that I played as much as I needed to win."
BASELINE MOBILITY
Sixth seed Nikolay Davydenko defused Fernando Gonzalez's serve with his mobility along the baseline to grab a sixth win in six meetings against the Chilean, 6-3, 7-5.
"If he has a second serve, I know I have a 90 percent chance to win the point," said the seemingly indefatigable 28-year-old.
Simon, seeded eighth, was the only one of three Frenchmen to get through the third round after he notched up a 6-3, 6-4 win over Czech Tomas Berdych.
Robin Soderling upset error-prone French fifth seed Jo-Wilfried Tsonga 6-3, 6-3 in their encounter under the open roof of the Qizhong central arena.
Soderling is among a handful of players still in with a chance of claiming one of three remaining spots up for grabs at the season-ending World Tour Finals in London next month.
"I know that if I play well, I have a chance, but this tournament won't decide who's going to play in London," said the ninth seeded Swede, who will face Feliciano Lopez on Friday. "There's still a lot of tennis to be played."
Swiss Wawrinka was losing 3-6, 7-6, 4-2 to Czech Radek Stepanek when abdominal pains caused him to withdraw, while French 11th seed Monfils was down 6-2, 3-0 to Ivan Ljubicic when he quit because of a back injury.
Ljubicic faces Nadal next.
