Jankovic has endured mixed fortunes in 2010
Third seed Jelena Jankovic crashed out of the China Open after being beaten by Serbian compatriot Bojana Jovanovski at the second-round stage in Beijing.
Jankovic lost 6-4 2-6 2-6 but paid tribute to her Fed Cup team-mate, saying: "It was a tough game. My opponent played really well.
"She was very solid off the baseline and she really gave me a hard time."
"I think she's doing very well and she's improving. I'm happy for her," added the world number six.
Last year's runner-up, Polish sixth seed Angela Radwanska, also made an early exit, beaten by Angelique Kerber.
The unseeded German twice fought back from 5-4 down to record a 5-7 7-6 (7-3) 7-5 victory.
Vera Zvonareva was made to work for her win over former world number one Dinara Safina in the first round, eventually going through 6-4 7-6 (8-6).
Wimbledon and US Open finalist Zvonareva said: "Dinara is a great player. It is very difficult to expect to play your best tennis in the first match of a tournament."
Danish world number two Caroline Wozniacki is the top seed in Beijing and is just two victories away from taking the top spot in the WTA rankings.
Defending champion Svetlana Kuznetsova went out on Sunday, as did Australian fourth seed Sam Stosur.
The Russian 10th seed was beaten 6-3 2-6 6-3 by Italy's Roberta Vinci, while Stosur suffered a 2-6 7-6 (7-5) 7-5 defeat by Latvia's Anastasija Sevastova.
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