BEIJING (AFP) - Top seed Dominic Thiem of Austria was upset in less than an hour by Albert Ramos-Vinolas at the ATP Chengdu Open on Friday (Sept 30), as the Spaniard sailed to a 6-1, 6-4 victory.

Ramos-Vinolas got off to a commanding start in the first set and never looked back, winning 84 per cent of his first serve points and scoring his first ATP head-to-head win over the world number 10.

Third seed Grigor Dimitrov of Bulgaria meanwhile bounced back from a first-set loss to prevail in a two-hour, 4-6, 6-4, 6-3 clash with Diego Schwartzman of Argentina, aided by 8 aces to Schwartzman's two.

Rising Russian star Karen Khachanov took 73 minutes to fell fourth-seed Feliciano Lopez 6-3, 6-4, conceding only six of his first-serve points and dropping 10 aces against the Spaniard.

The 20-year-old, 1.98m Russian advances to his first ATP World Tour semi-final, where he will face sixth-seed Viktor Troicki, who notched a 6-3, 7-6(4) victory over Kevin Anderson of South Africa.