Star Indian shuttler PV Sindhu had to dig deep to beat Denmark's Line Christophersen in the women's singles opening round, while Lakshya Sen stunned world No. 4 Loh Kean Yew of Singapore in men's singles of the Malaysia Masters, on Wednesday. Sindhu, seeded sixth, had to toil for one hour and two minutes to get the better of Christophersen 21-13 17-21 21-18 and maintain her superiority over the world no. 33 Dane, who the Indian had defeated four times earlier. The two-time Olympic medallist Indian, ranked 13th in the world, will next play Japan's Aya Ohori.