A bidder stepped into the unknown Sunday afternoon, paying 2.8 million yuan at auction to snap up the sponsorship rights to Bird's Nest Stadium's staging of a Guinness world record attempt at endurance tightrope walking.

After the auctioneer opened the bidding, a 40-minute seesaw battle between bidders number 99 and 9 ensued.

Hong Changshan, bidder number 99 and chairman of Xiangfan Jialong Co Ltd, told METRO the final price he paid far exceeded his bottom line of 1 million yuan.

"I didn't want to lose face so I insisted on raising my bid," he said.

Hong said he initially had no plans to take part but heard about the event during a tour in the capital a few days ago.

"I plan to advertise 'China's Xiangfan' on all the advertising spaces in order to show my thanks to our local government," said Hong, who is from Xiangfan, a 19,800-sq-m city in Hubei province.

Li Chunlin, bidder number 9 and an agent for a Guangdong-based washing products company, said he was frustrated that he did not win the auction but had to back out after "a cell phone call from the boss".

Bird's Nest Stadium, which is also known as National Stadium, is the scene of a world record attempt that began last Monday by tightrope walker Adili Wuxor.

The 38-year-old plans to break the Guinness World record by living in a 60-m-high cabin on the roof of Bird's Nest and walking the tightrope continuously for 60 days.

The winning bidder now has the right to advertise on 12 billboard spaces in the stadium and broadcast a 30-second advertisement on the big screens four times an hour.

In addition to the headline bid, Hong won four other bids on Sunday, snagging the right to advertise on Wuxor's wardrobe (500,000 yuan), his cabin (330,000 yuan) and during his first embrace when he gets back on the ground (15,000 yuan).

Beijing Dazhong charity foundation, a public foundation affiliated to China Charity Federation, won the bid for the right to advertise on Wuxor's cell phone, paying out 100,000 yuan.

Bid soliciting was launched on April 30 and attracted eight companies, according to Beijing Yihai Auction Co Ltd, which operated the competition.

Zhao Xiaokai, chief planner with Yihai, told METRO he felt "satisfied" with the auction's closing prices.