Novak Djokovic breezed into the third round of the Shanghai Masters with a 6-2, 6-1 victory over Martin Klizan on Wednesday.
The World No 1 dropped only three games against Klizan.
Eyeing a third Beijing-Shanghai double, Djokovic converted half of the 10 break points that came his way to sweep aside his error-prone Slovak opponent.
"Klizan is a very flashy player," Djokovic, who won last week's China Open in Beijing, said.
"He can play very fast but with a tendency to make a lot of unforced errors, which he did. He made my life a bit easier on the court today.
"I was trying to serve, move him around the court. Just played as much as I needed. It was enough to win," the Serbian said after improving to a 13-match winning streak.
But Ivo Karlovic made sure Rafael Nadal had to work a lot harder to advance.
Nadal eventually won through 7-5, 6-7(4), 7-6(4) after two hours and 43 minutes of a closely-fought encounter.
After trailing 3-5 in the opening set, Nadal produced a series of stunning returns to break Karlovic in the 10th game to claim the lead.
The Croat, however, refused to give up, prevailing in the second set tie-break to force the decider, which again went to the wire before the Spaniard claimed victory.
French Open champion Stanislas Wawrinka also maintained his winning run with a 7-6(3), 6-3 victory over Viktor Troicki to set up a third-round contest with Marin Cilic.
Third seed Andy Murray beat American Steve Johnson 6-2, 6-4, Bernard Tomic eliminated seventh seed David Ferrer 6-4, 6-2 and Japan's Kei Nishikori overcame Australian Nick Kyrgios 1-6, 6-4, 6-4.
