The top-seeded player in the tournament is from Spain -- David Ferrer. He and No. 2 Andy Roddick play first-round matches Thursday. Both were given extra rest following Spain's victory over the United States in the Davis Cup semifinals in Madrid last week.
"When you are young and you see a lot of people playing tennis and you can practice with them, your level goes up quickly," said Robredo, who was left off the Davis Cup team for the semifinal. "This is helping Spanish tennis."
Added Ferrero: "In the last few years we have improved on hard courts, also on grass. So we can play anywhere now and that is one of the keys to having a lot of players in the top 100."
Robredo was the runner-up in Beijing a year ago, losing in the final to Fernando Gonzalez of Chile. Gonzalez is back this year and seeded No. 3.
Six Spaniards started in the first round of the 32-player draw, a strong turnout even without top-ranked Rafael Nadal.
The China Open is a men's and women's event being played at the Beijing Tennis Center. It moves next year to the tennis venue that was built for the recent Beijing Olympics.
The ATP and WTA tournaments are being played together to make up for time lost from the schedule because of the Beijing Olympics.
In the WTA event, two Serbians are the top seeded players -- No. 1 Jelena Jankovic and No. 2 Ana Ivanovic. Jankovic plays Wednesday, with Ivanovic set for Thursday. The draw also features two others in the top 10 -- Russian players Svetlana Kuznetsova and Vera Zvonareva.
Tuesday was supposed to be a showcase for Chinese women, but it didn't work out that way. The five Chinese women in the tournament all played first-round matches, and four lost.