Double Olympic medallist PV Sindhu was knocked out but defending champion Lakshya Sen looked in fine fettle on way to a straight-game win over compatriot HS Prannoy in the India Open here on Tuesday.

Former champion Saina Nehwal eked out a 21-17, 12- 21, 21-19 win over world No. 24 Mia Blichfeldt of Denmark in her opening match.

World No. 7 Sindhu, a former champion, went down 12- 21, 20-22 to Thailand’s world No. 30 Supanida Katethong.

World No. 12 Sen, seeded seventh, avenged his loss to world No. 9 Prannoy after his opening round reversal at the Malaysia Open, with a 21-14, 21-15 win.

Sindhu struggled against the left-handed Supanida, who was precise in her returns and looked more in control in the rallies to take the opening game in the Super 750 badminton tournament.

The former world champion fought hard in the second game as she moved from 12-17 to grab one game point at 19-20. She had, in fact, left the court after the opponent’s return was called out. But a video referral showed that the shuttle had actually kissed the line, handing her opponent a chance to close the match, and she did it in style after Sindhu went wide.

Reigning champions Satwiksairaj Rankireddy and Chirag Shetty also produced a clinical display to storm into the second round after beating Scotland’s Christopher Grimley and Matthew Grimley 21- 13, 21-15 in their men’s doubles opener.

Commonwealth Games champion Sen will next take on Denmark’s Rasmus Gemke, who knocked out two-time world champion Kento Momota 21-15, 21-11 earlier in the day.

Women’s duo Treesa Jolly and Gayatri Gopichand notched up a 22-20, 17-21, 21-18 win over France’s world No. 29 Margot Lambert and Anne Tran in their opener.