Despite falling behind early, the second-seeded Roddick defeated fellow American Brendan Evans 6-4, 6-3.
Seeded No. 1, Ferrer was never in his second-round match, falling 6-3, 6-3 to Dudi Sela of Israel, who is No. 92 in the ATP rankings - 87 spots behind the Spaniard.
Both Roddick and Ferrer had byes in the first round and some extra days off following Spain's emotional Davis Cup semifinal victory last weekend over the United States in Madrid. But it was Roddick who was ready to rebound despite falling behind early against Evans.
"From 4-2 down in the first set I started feeling a little better,'' Roddick said. "It's a little tough going from clay last weekend in Spain to dealing with the jet lag and what not.''
Roddick was mentored by Andre Agassi as a young player. After the match, he gave his younger compatriot a few tips.
"I told him (Evans) I thought he took his foot off the accelerator a little bit when he was up in the match,'' Roddick explained. "And maybe he stopped being as aggressive as he was to get in the lead, and that allowed me to get a rhythm.''
Roddick also acknowledged the outdoor hard court in Beijing suits him better than the red clay in Spain.
"I'm able to do some more stuff on a quicker court, a hard court,'' he said. "Clay limits my game a little bit more.''
Ferrer beat Roddick in a grueling five-set match in the Davis Cup. He didn't look for excuses Thursday, noting Sela had also played Davis Cup against Peru in Israel before traveling to China.
"I was maybe a little bit tired and didn't sleep well these last two nights,'' Ferrer said. "That's no excuse. He played better than me. It's not a good day for me.''
Sela has never reached the semifinals of a top-line ATP event, and will get his chance against Tommy Robredo. The sixth-seeded Spaniard reached the quarterfinals by beating Ivo Minar of the Czech Republic 6-2, 6-3. In another second-round match, No. 7 Rainer Schuettler beat Jean-Claude Scherrer 6-1, 6-4.
In two other men's second-round matches, Bjorn Phau of Germany beat Sam Querrey of the United States 5-7, 6-3, 6-4, and Juan Carlos Ferrero of Spain defeated Fernando Verdasco 7-5, 6-4.
On the women's side, Zheng Jie of China gained a quarterfinal berth by beating Ai Sugiyama of Japan 6-1, 6-2. Zheng is the only Chinese woman remaining in the draw after four others lost in the first round.
No. 2 Ana Ivanovic also reached the quarterfinals, beating Alize Cornet 6-1, 7-6 (1). And No. 4 Svetlana Kuznetsova advanced by defeating Russian countrywoman Alla Kudryavtseva 6-2, 6-3.
In other women's second-round matches, Dominika Cibulkova of Slovakia beat No. 8 Anna Chakvetadze of Russia 6-3, 6-2, and No. 5 Vera Zvonareva of Russia advanced by defeating Francesca Schiavone of Italy 7-6 (5), 6-2.
Defending champion Agnes Szavay of Hungary was ousted by Anabel Medina Garrigues of Spain 6-2, 6-2.
The China Open is a combined ATP and WTA event, played together to make up for scheduling time lost during the Beijing Olympics.
Sela upsets No. 1 Ferrer; Roddick advances
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