Two-time Olympic medallist PV Sindhu and Thomas Cup star HS Prannoy secured contrasting wins to enter the quarter-finals of the Malaysia Open Super 750 badminton tournament here on Thursday.

Unseeded Prannoy, who won all his matches during India’s historic Thomas Cup triumph this year, registered the biggest upset of the day when he eliminated World No.4 Chou Tien Chen of Chinese Taipei 21-15, 21-7 in contest that lasted more than 30 minutes.