With the biggest on-paper upset in Sony Ericsson WTA Tour history, Dinara may have relinquished the No.1 ranking on Monday, as the Russian lost to No.226-ranked wildcard Zhang Shuai, 75 76(5), in the second round of the China Open in Beijing.

Zhang, 20, is now the lowest-ranked player ever to beat a reigning No.1, bettering the No.188 ranking held by Julie Coin as the Frenchwoman outdid Ana Ivanovic at last year’s US Open. Dinara had her chances, leading by a break early on in both sets and even having a set point in the second set.

“I’m having some bad losses. So many matches that are very close, ones I should win, having set points or match points every time,” Safina said. “It’s very disappointing. I’d like to take a break now. I’m very upset with myself.”

With Serena Williams’ victory over Ekaterina Makarova on Tuesday, she will return to No.1 when the new rankings are released Monday. Dinara assumed the top spot from Williams on April 20.

Dinara withdrew from her second round doubles match alongside Svetlana Kuznetsova due to a back injury suffered in singles.

Through to Round 2 in Beijing

No.1 seed Dinara defeated Roberta Vinci, 64 64, on Sunday in the first round of the $4.5-million China Open in Beijing.

Dinara raised her career record against the 26-year-old Italian to 4-0. Next up for her is 20-year-old Chinese wildcard Zhang Shuai.

Dinara is playing this event for only the second time in her career, having lost in the round of 16 in 2004.

In doubles, Dinara and fellow Russian Svetlana Kuznetsova advanced to the second round on Saturday with a 60 60 rout of Jill Craybas and Alexa Glatch.