document: The National Stadium - or Bird's Nest - was used at the 2008 Olympics.
  "When you plan someone's career like Joshua you tend to plan in advance," said Hearn, who saw Joshua stop Charles Martin last month to win the title.
  "I think we're two years from saying we can sell out the Bird's Nest in China."
  Hearn is the father of Joshua's promoter Eddie, and chairman of the fighter's Matchroom stable.
  He identified China's 2008 Olympic silver medallist Zhang Zhilei, who has built an unbeaten professional record of eight fights since basing himself in Las Vegas, as a potential opponent for 26-year-old undefeated Joshua.
  "Sometimes these things don't happen because people get beaten, but our job is about creating these kinds of moments," he added.
  Joshua will make the first defence of his title against American Dominic Breazeale in London next month.
summary: Great Britain's IBF world heavyweight champion Anthony Joshua could make a defence of his title at Beijing's National Stadium, according to promoter Barry Hearn.