Novak Djokovic fired an ominous warning to his rivals on Thursday, powering into the Shanghai Masters quarter-finals as defending champion Andy Murray finally made his bow with an easy win.

The Serbian second seed, looking to wrestle the world No.1 ranking from rival Roger Federer, barely broke sweat against Spain's Feliciano Lopez, wrapping up a straightforward 6-3 6-3 victory in front of enthusiastic fans.

In-form Djokovic, fresh from his third China Open title in Beijing on Sunday, struck 12 aces and took advantage of some below-par serving by the left-handed Lopez, breaking him three times.

A powerful backhand down the line sealed the match for the 25-year-old and set up a clash against either sixth seed Janko Tipsarevic of Serbia or German veteran Tommy Haas, who play later.

"I'm not very well known around the Tour for big serving," said Djokovic. "But so far in this tournament, and also in Beijing, it has been working very well for me.

"It has been giving me a lot of free points, a lot of confidence into the matches."

US Open champion Murray, 25, proved far too strong for Ukraine's Alexandr Dolgopolov, serving consistently well and seizing on five out of six break points to win 6-2 6-2 in just 57 minutes.

It was the first match of the tournament for the Scot, who had a walkover into the third round. The top eight seeds received a first round bye.

Earlier, fifth seed Jo-Wilfried Tsonga struck 11 aces in seeing off the challenge of former Australian Open finalist Marcos Baghdatis of Cyprus 6-2 7-6 (7-2) in a contest containing a surprising eight breaks of serve.

The Frenchman said he was happy with his game and was focusing on the task in hand rather than on London. He is currently in line to secure the last singles berth in the elite eight-man field.

"For the moment I think about this tournament," he said. "You know, I try to play my best tennis. After, of course for me London is a goal. But I also have another goal, to win some tournaments and try to beat the guy before me."

Czech fourth seed Tomas Berdych, sixth in the Race to London, set up a quarter-final meeting with Tsonga after fending off a barrage of 17 aces from American Sam Querrey to win 6-2 6-7 (3-7) 6-4.

Radek Stepanek of the Czech Republic upset eighth seed John Isner of the United States 6-4 6-7 (5-7) 6-3.