Michael Ballack admits he regrets leaving Chelsea in 2010.

Ballack wanted a two-year contract but Chelsea's policy only allowed players over the age of 30 to sign one-year extensions.

He told Sky Sports: "Carlo [Ancelotti] wanted me [to stay] but the club made a decision to only give players of that age a one-year contract. I wanted two.

"Today, I can say maybe it was wrong. I should have stayed, even for that one year.

"I could never imagine that I would go back to [Bayer] Leverkusen. Until the last day, I actually thought we would find a way at Chelsea. I was really hoping I could stay until the end."