The badminton "grand slam" winner Lin Dan pulled out of Hong Kong Open Super Series before the quarterfinals here on Friday as he did in the China Open earlier this month.

Xia Xuanze, men's singles coach of the Chinese national team, told reporters that the decision was made on Friday morning when Lin Dan felt uncomfortable in his waist.

"He is too tired after so many matches in the past few weeks," said Xia.

Lin also played two rounds and withdrew from the quarterfinals in the China Open while in last year's Hong Kong Open, he quit without playing a single match.

The 27-year-old Chinese sports star was under rumors of finally marrying former national teammate Xie Xingfang, women's singles world champion in 2005 and 2006, after a six-year relationship.

Lin has been frequently asked of the possible marriage time since the Asian Games which was held in Xie's hometown. The latest news came out recently in Hong Kong where Lin was pushed to ask pop singer Eason Chan for a proposing song during a commercial conference before the HK Open.

It was then reported that Lin's mother revealed that Lin, an armyman, has applied to the army for a marriage, and they might register in Lin's hometown Fuzhou recently.

However, neither of the couple has confirmed of the news. Lin refused all interviews after both matches here at the HK Open.

Vietnam's eighth seed Nguyen Tien Minh got through to the semifinals.