Jose Mourinho has told Michael Ballack to decide before the World Cup if he will join Chelsea.
Ballack has confirmed he is in 'serious negotiations' with the Blues, who are set to claim a second successive Premiership title.
Mourinho is full of praise for the 29-year-old midfielder but has now given him an ultimatum.
The Chelsea boss told Germany's Bild am Sonntag newspaper: "He has got everything. I am impressed by his intelligence on the pitch.
"I have been watching him for a long time. I like him as a human being. But he needs to make a decision before the start of the World Cup."
Mourinho also revealed what Ballack, who was on target in Bayern Munich's 2-0 victory over Bielefeld on Saturday, could expect from a move to England.
"In England we have three matches a week," he added. "That's why we never practice twice a day. Normally we're just playing and travelling. It lets you tire fast."
