Roddick defeated Russia's Igor Kunitsyn, who is ranked 99 in the world, 7-6 (9-7) 6-2 6-3.

BBC: Australian Open: Federer survives scare from Simon

Sixth seed Nikolay Davydenko was the first man to reach the third round, seeing off Igor Kunitsyn 6-4 6-2.

BBC: Injured Roddick out of Shanghai

Querrey, who beat unseeded Russian Igor Kunitsyn 6-3 6-4, is hoping to build on his L.A. Open title last weekend.

CNN: Roddick victorious on return from injury

That leaves their fate in the hands of world number six Nikolay Davydenko, 20th-ranked Igor Andreev, Dmitry Tursunov (26) and Igor Kunitsyn, who is ranked 76 in the world.

BBC: Safin pulls out of Davis Cup tie

In other second-round matches, eighth seed Janko Tipsarevic lost to Viktor Troicki 6-3 6-4 in an all-Serbian match, and Igor Kunitsyn of Russia ousted Robby Ginepri of the United States 6-4 6-3.

BBC: Jankovic battles past Dushevina