German international captain Ballack has held negotiations with Chelsea over a possible summer switch but Portuguese coach Mourinho wants the player to make a decision before the World Cup kick off on June 9.

"He has to have made a decision before the World Cup," Mourinho said in an interview with Bild am Sonntag.

Chelsea, bankrolled by billionaire Russian oil tycoon Roman Abramovich, are reportedly prepared to make Ballack the world's highest-paid player with a weekly salary of 121,000 pounds (177,600 euros, 210,900 dollars).

"For me Ballack is one of the best players in the world," enthused Mourinho. "He has everything and his intelligence on the pitch impresses me. I also like him as a person."

The 29-year-old Ballack is available on a free transfer after turning down a four-year contract extension at Bayern.

Real Madrid and Manchester United registered their interest but only Chelsea seem willing to match Ballack's personal demands.