Shanghai - Reigning Shanghai Masters champion Novak Djokovic has survived a scare as he overcome his 85th-ranked opponent to make the quarter-finals Thursday, while Britain's Andy Murray crashed out.
Meanwhile, third seed Roger Federer eased through, beating Spaniard Roberto Bautista Agut 6-4, 6-2.
Djokovic, the top seed in Shanghai, arrived at the tournament in the form of his life, but was forced into a third set by Mikhail Kukushkin as he claimed a hard-fought 6-3, 4-6, 6-4 victory.
The world number one began in predictable style, breaking his opponent on his final service game in the opening set as he looked to be heading for a routine win.
But in the second set, the Kazakhstani proved to be no pushover against an opponent who was seeking his 27th successive victory on Chinese soil.
The 26-year-old broke the Serb on his opening service game, and then staged his first attempt to take the set as he earned a break-point with the scores at 5-3.
Djokovic danced jubilantly when he saved set-point, and moments later appeared to have snuffed out the unexpected challenge when he broke back.
But Kukushkin refused to submit to the 7-times Grand Slam winner and stole Djokovic's serve again to set up a decider.
Djokovic battled hard in the third set, losing his trademark coolness as he shouted and pumped his fist at almost every point won.
He made a breakthrough in the fifth game, taking Kukushkin's serve to march to a 4-2 lead, which ended any further heroics from his opponent.
Djokovic will face David Ferrer in the quarter-finals Friday after the Spaniard overcame 11th seed Murray 2-6, 6-1, 6-2.
The result was a blow to Murray's hopes of making the end-of-season World Tour Finals.
The world number 11 took the first set with ease before crumbling, as Ferrer powered back to leapfrog Murray into ninth place in the race to reach the eight-man year-ender.
It was a crushing setback for Murray, who has won seven of their previous 12 meetings and must now scramble if he is to make next month's season finale in London.
"Hopefully I can play well the last couple of tournaments, try and make a push for London," he said following his defeat.
A day after Rafael Nadal was one of five top-10 players to fall, Murray started the third-round match brightly, going 5-1 ahead within 25 minutes before closing the first set 6-2 with his fifth ace.
But fifth seed Ferrer took the initiative in the second set with increasingly powerful groundstrokes, snuffing out the threat from Murray's aggressive serving game.
The 27-year-old Scot earned just one break point in the second set, as he made a series of mistakes dealing with Ferrer's topspin.
And the Spaniard continued to torment early in the decider, breaking serve at his second attempt after Murray drove a routine groundstroke into the net.
He then broke again to charge ahead at 5-2 before sealing it in one hour and 55 minutes.
Djokovic, Nadal and Roger Federer have already qualified for the World Tour Finals, leaving five spots up for grabs.
But most of the players gunning for the remaining positions have already lost in Shanghai, with only Tomas Berdych, in seventh place, remaining.
And the Czech sixth seed strengthened his bid when he won his third round match against Croatian Ivo Karlovic 6-3, 6-4 in just one hour four minutes.
Berdych will meet Gilles Simon in the last eight, after the French player continued his fine form at the tournament, dumping out Malek Jaziri of Tunisia 6-2, 6-3.
Simon had ousted Australian Open champion Stan Wawrinka in the second round.
Elsewhere, Feliciano Lopez of Spain powered into the quarter-finals after beating 13th-seed American John Isner 6-3, 6-4.
Lopez, who dumped out Nadal in the last round, will meet Russian Mikhail Youzhny in the quarters after he overcame Juan Monaco of Argentina 5-7, 6-3, 6-2.
Meanwhile, Julien Benneteau of France beat American Jack Sock 6-3, 6-4, and will meet 17-times Grand Slam winner Federer in the next stage.
The ATP World Tour Masters 1000 event concludes in Shanghai on Sunday.