Top-seeded Novak Djokovic overcame a tough challenge on Thursday, outlasting Fernando Verdasco of Spain 7-5, 2-6, 6-2 in a see-saw match to reach the quarterfinals of the China Open.

Djokovic, who had lost his last two matches against Verdasco, won the first three games en route to taking the first set, but the Spaniard fought back in the second by breaking the top-ranked Serb in the third and seventh games.

Djokovic will next take on American Sam Querrey, who upset sixth-seeded Stanislas Wawrinka of Switzerland 6-3, 7-6 (2).

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