After the final Gland Slam of the year in Flushing Meadows, there is a migration to Asia as part of the Women's Tennis Association's Asian swing, but the tight end of season schedule may be a bridge too far for some players.

The line up for the last tournaments of the year has been hit by withdrawals as the players zip across the vast continent between Japan, China and Singapore with barely a break.

Maria Sharapova retired from Wuhan and withdrew from the China Open with an injury, leaving a question mark over whether she will make it to the WTA Final in Singapore, while world number one Serena Williams announced an early close to her season.

The WTA opened an office in Beijing in 2008, and has since added eight tournaments in China, bringing to 23 the total number in Asia -- 40 percent of the tour.

"Tennis in Asia has never been better than it is now," said Melissa Pine, tournament director of the season-ending championship, which was shifted to Singapore last year as part of a five-year deal.

The Wuhan Open was one of three new events launched in China last year, created off the success of hometown star and two-time Grand Slam-winner Li Na.

But Li never played at the event, retiring on the eve of the inaugural tournament plagued by injuries picked up earlier in the season.

Four retirements and numerous shock defeats thinned the ranks of the top seed players at this year's Wuhan Open.

Caroline Wozniacki and two-time major-winner Victoria Azarenka exited on day three, and defending champion Petra Kvitova fell on day four, with all of them saying they were tired at the end of a tough year.

World number two Simona Halep admitted that she was struggling to stay focused the day before she was knocked out of the Wuhan Open by breakthrough Briton Johanna Konta.

"It's very tough. Every day I'm thinking about the holiday. But I have to stay concentrated," she said before moving onto Beijing for the China Open.

Konta might have been expected to cement her 21/23 win run at the China Open, but after losing to Venus Williams the British number-one-in-waiting announced that she had withdrawn.

"I'm going to be heading home. I decided to withdraw from Beijing just because... I would have had to already fly tomorrow and play tomorrow," the 24-year-old said.

Swiss youngster Belinda Bencic played in Wuhan the day after she lost the final of the WTA Pan Pacific Open in Tokyo to Agnieszka Radwanska, and then retired just 38 minutes into her second match.

But the 18-year-old said she would play in Beijing.

"I will do my best to be there, it is just the end of the season and all the players are really tired," Bencic said.
Source: AFP