Top seed Novak Djokovic overcame a second set meltdown to beat Spaniard Fernando Verdasco 7-5 2-6 6-2 and reach the quarter-finals of the China Open on Thursday, keeping alive his hopes of clinging on to his world number one ranking.
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 Spaniard 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 (2) in 76 minutes.
Djokovic, 26, 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.