World No 30 HS Prannoy, who is on a comeback trail after recovering from a stomach problem, on Tuesday registered one of his biggest upsets in recent times as he beat five-time champion Lin Dan of China to advance to the third round of the ongoing World Championships. Prannoy,who has a reputation of producing big upsets when on song, defeated 11th seeded Dan 21-11, 13-21, 21-7 in a match that lasted for 62 minutes.