Fullerton, June 26 -- India's Rounak Chouhan created the biggest upset of the US Open badminton tournament here on Thursday when he packed off World no 6 and men's singles top seed Chou Tien Chen of Chinese Taipei in straight games.

World No. 80, Chouhan, who was part of India's bronze medal-winning world junior campaign, defeated Chou 21-17, 26-24 to set up a last eight clash against Misha Zilberman of Israel, according to a release.

The 18-year-old India kept the pressure on his more experienced opponent from the start, and though Chou kept his nose ahead till 17-15, Chouhan won six straight points thereafter to pocket the opening game.

Chou was the dominant player for most of the second game as he commanded a 17-11 lead before Chouh...