Ballack told BBC Sport: “I haven’t signed yet but I have agreed for another year.”
The German midfielder expects AC Milan coach Carlo Ancelotti to join the club this summer.
The 32-year-old continued: “It’s not done yet but it looks like he will be coach.”
He added: “I haven’t worked under him and I don’t know him very well but you can see from the work he has done at Milan that he is a successful manager.”