Pop King Jay Chou dances with ex-girlfriend Jolin Tsai during his Taipei concert. [CRI]

Pop king Jay Chou kicked off his world concert tour on June 11, the same day of the South Africa World Cup. It's Chou's fourth concert tour since he entered the entertainment circle 10 years ago.

On the third day of his Taipei stop, Chou invited his ex-girlfriend singer Jolin Tsai to be the guest singer.

Chou and Tsai were involved in a high-profile breakup in February 2005, after Chou was photographed with news anchor-turned-television host Patty Hou in Tokyo. However, some recent reports have asked if the two are dating again. Chou broke up with Patty Hou in 2006.