The defending champion, aiming for his fourth China Open title in five years after missing the 2011 tournament through injury, will lose the top spot next week if in-form Rafa Nadal reaches the final in Beijing.
In the quarter-finals, the Serb will face American Sam Querrey, who caused an upset by defeating sixth-seed Swiss Stanislas Wawrinka 6-3, 7-6 (7-2) in 76 minutes.
While much is being made of the No 1 battle, the 26-year-old six-times grand slam champion insists winning, rather than ranking points, is his sole focus when he takes to the court.
“I try to do what I need to do, and that is to win the matches,” Djokovic explained.
“Rankings will change. They change all the time. Over the years it has been the case. But you can’t think too much about it. Your job is to win as many matches as possible and the rankings will follow the results that you make.”
The Serb wasted an early break of serve in the first set and had to wait for the final game to break Verdasco again and seal the opener.
Using his forehand to great effect Verdasco fought back, breaking Djokovic’s serve twice in the second set to take the Serb into a centre court decider.
Reigning Australian Open champion Djokovic, without a title since the Monte Carlo Masters in April, quickly re-established his superiority to snuff out any chance of a shock.
“(It was a) lack of concentration from my side,” Djokovic added. “I had some chances at the start of the second set, and I managed to allow him to come back into the match and start playing well.
“But, again, the important thing is that in the third set I regained the focus and the patience also, decreased the unforced errors, and managed to get a win, which is what counts.”
In the women’s draw, Serena Williams won her 70th match of the year and also improved her record to 8-0 against Maria Kirilenko with a hard-fought 7-5, 7-5 victory.
She had to work hard for this one, though. The unseeded Russian broke Williams to take a 5-4 lead in the first set, then held three set points on her serve before Williams recovered. Kirilenko also broke Williams in the second set and took a 4-2 lead before faltering down the stretch.
“I just thought, what else can I do except fight for this point and the next point?” Williams said. “Maybe I got lucky a little bit – I just started to relax and kind of swing and not think about it too much out there. I’m obviously just really happy to get through this match today.”
In another match, Serbia’s Jelena Jankovic routed Spaniard Carla Suarez Navarro 6-0, 6-0. It was only the third “double bagel” of Jankovic’s career, the last one coming against another Spaniard, Virginia Ruano Pascual, in Beijing in 2007.
Third-seeded Agnieszka Radwanska of Poland, tenth-seeded Roberta Vinci of Italy and unseeded Lucie Safarova of the Czech Republic also advanced.
In Tokyo, defending champion Kei Nishikori booked his place in the quarter-finals of the Japan Open with a straight-sets win over Feliciano Lopez. Nishikori eased to a 7-6 (7/4) 6-0 victory to set up a last-eight meeting with another Spaniard, sixth seed Nicolas Almagro, who was a 6-4, 6-2 winner over Argentina’s Horacio Zeballos.
Third-seeded Milos Raonic of Canada overpowered Jeremy Chardy of France 6-4, 6-3 to advance to the quarter-finals of the Japan Open.
Raonic, coming off a win at the Thailand Open on Sunday, hit 17 aces in the match and will next face Slovakian Lukas Lacko, who beat qualifier Edouard Roger-Vasselin of France 7-5, 6-4.
“He doesn’t have anything to lose,” Raonic said. “As usual, I’ll focus on my serve. He’s a very dangerous and powerful player so I will have to play a tight, disciplined game.”
Top-seeded Juan Martin del Potro will play Alexandr Dolgopolov of Ukraine in the quarter-finals today.