Under-pressure Peng tells Li Na - wish you were here

Peng Shuai admits she feels the huge burden of Chinese expectation in the absence of superstar Li Na after stunning Polish fourth seed Agnieszka Radwanska at the US Open on Wednesday.

The 28-year-old, ranked at 39, clinched a shock 6-3, 6-4 win for a fourth career victory over a top five player but first at a Grand Slam.

The win immediately swung the spotlight on the softly-spoken Tianjin native after world number three compatriot Li, the Australian Open champion and 2011 French Open winner, was forced to skip the tournament with a knee injury.

"I prefer to have Li Na here. They (Chinese fans) didn't watch me...now there is more pressure. It's not easy to handle that. I just want to focus and enjoy my tennis," said Peng who added that at least having five other Chinese in the main draw helped ease the burden.

"When they say Li's not going to play Montreal, Cincinnati, and also the US Open, it was big news. But this year is one of the best with six Chinese girls in the main draw."

Of those six, three remain with Peng in the last 32 while qualifiers Wang Qiang and Zheng Saisai have made the second round.

Wednesday's win was a repeat of Peng's defeat of Radwanska, the champion in Montreal in the run-up to the tournament, at the same stage in New York in 2010, her only triumph in four meetings with the Pole.

Peng also wiped out the misery of her last clash against Radwanska when she squandered two match points in losing their fourth round encounter at the 2011 Australian Open.

Peng, who has reached six singles finals in her career but has yet to lift a title, said she had been inspired by Li to keep playing despite twice being tempted to call a halt to her career.

"I have learned a lot from Li. She is one of the best players in the world. Now I will try to keep going.

"There is still a lot of work to do but I want to keep enjoying my tennis."

- Doubles number one -

Despite her admiration for her compatriot, Peng has already achieved something that Li has not.

In February this year she became the first Chinese player to reach number one in the world when she went top of the doubles charts thanks to her success with Taiwan partner Hsieh Su-Wei.

Peng sent down 28 winners on Wednesday in a gruelling clash on the Louis Armstrong Stadium which featured a series of brutal flat-hitting rallies in temperatures bursting through the 30-degree barrier.

"Radwanska is a tough player. I had to do a lot of running, but I fought," said Peng who took victory on a third match point.

"I wanted to make it this time. I had two match points against her in 2011 in Australia and lost. This is just amazing."

As Peng goes on to face Italian 12th seed Roberta Vinci for a place in the last 16, Radwanska was forced to contemplate another disappointing US Open.

The Wimbledon runner-up in 2012 has reached at least the quarterfinals at the All England Club and Australian and French Opens.

But the 25-year-old has still yet to get beyond the fourth round in New York despite nine attempts.

"Peng is a very solid player, very consistent from both sides, playing very good from the back. Very consistent," said Radwanska.

"In the important moments I think she was just playing a little bit better.