Ferrer, ranked No. 5 in the world and 87 places ahead of Sela, had a bye into the second round at the Beijing tournament after helping Spain defeat the United States last weekend in the Davis Cup semifinals in Madrid.
Ferrer didn't look for excuses, 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.''
Ferrer suggested he may have been drained by a grueling five-set Davis Cup win over America's Andy Roddick.
"I didn't fight a lot because psychologically I'm not in a good moment now.''
Second-seeded Roddick defeated fellow American Brendan Evans 6-4, 6-3 to reach the quarterfinals.
China's home favorite Zheng Jie also gained a quarterfinals berth, 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.
In another early result, No. 4 Svetlana Kuznetsova of Russia beat countrywoman Alla Kudryavtseva 6-2, 6-3, to reach the quarterfinals.
The China Open is a combined ATP and WTA event, played together to make up for scheduling time lost during the Beijing Olympics.
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