World No. 1 Roger Federer downed Taiwanese qualifier Yen-Hsun Lu in their second-round match at the Shanghai Masters on Wednesday.

Federer came under pressure from the world No. 62 at times in a 6-3, 7-5 win.

In the third round, Federer will face fellow Swiss player Stanislas Wawrinka, seeded 13th.

Earlier, Wawrinka won a close-fought battle against Denis Istomin of Uzbekistan 6-4, 4-6, 6-4.

Elsewhere, sixth seed Janko Tipsarevic dispatched another Serbian player Viktor Troicki 6-2, 7-6(3).

Tipsarevic will face German veteran Tommy Haas in round three.