John Hartson has offered his tip for Sir Alex Ferguson's successor at Manchester United.

Former Arsenal and West Ham United striker Hartson says there's only one man for the job, and that's... Martin O'Neill, the Sunderland manager.

"Only one man could have got Sunderland out of the hole they were in." Hartson tweeted. "That's the genius Martin o'neill.. Next man united manager."

He followed that assertion by adding: "Moyes not in the same class. Mourinho is proven but is a liability with his behaviour. Pep taking a break not sure for how long..o'neill cert."