Nadal - currently ranked eighth in the world - endured another robust test for the second time in successive days in Beijing after his 6-4 6-4 win over Di Wu in the first round.
He managed to overhaul the Canadian in the first set tie-break 7-3 before one break of serve in the second was good enough to see the Spaniard complete victory in one hour and 47 minutes.
Nadal will face Jack Sock in the last eight after the American completed a comfortable success against Andreas Haider-Maurer.
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Tomas Berdych.

Image credit: AFP

There was no such smooth passage for Tomas Berdych, who slumped to a shock 6-4 6-4 defeat to world number 37 Pablo Cuevas.
Berdych had won his first tour of the year in Shenzhen, but threw in 32 unforced errors in losing in one hour and 46 minutes.
“I made one tournament title, the other one didn't go my way,” said Berdych.
“(I’m) just going to try to do well in the third one, my last one. It's always a difficult part of the year. We have to travel a lot. The conditions are always very different, very difficult, week by week here in China.
"It's not easy to adjust … It's the same for all of us just ahead of the last and big tournament.”
Nadal's fellow Spaniard David Ferrer was also a winner on Wednesday in completing a 7-6 (7-5) 6-2 win over Lukas Rosol in straight sets.
[Nadal made to work to win Beijing opener, Djokovic cruises]
China Open - second round results
Y.H Lu beat V. Troicki 6-4 7-5
P. Cuevas beat T. Berdych 6-4 6-4
J. Sock beat A. Hider-Maurer 6-3 6-1
I. Karlovic beat G. Garcia Lopez 7-5 7-6
D. Ferrer beat L. Rosol 7-6(5) 6-2
R. Nadal beat V. Pospisil 7-6(3) 6/4
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