When do the tickets for the Shanghai Rolex Masters 2011 go on sale?

When do the tickets for the Shanghai Rolex Masters 2011 go on sale? We plan to watch it but we're from the Philippines, so we need to book on-line. When is the earliest day that they make it available? We're just worried we it would be sold out so we're planning to buy as early as the tickets go on sale, but they don't have any info on it on their website. Please help!|||Last year, tickets went on sale on May 27th, so I would expect it to be the end of May this year too. Keep an eye on the website Http://Masters.taobao.com for any updates / changes.