One of the few guarantees of Sunday's derby is Manchester United will not revert to a back three. Four times Ole Gunnar Solskjaer selected an extra centre-back against City; United won twice and lost twice.
The latter defeat was one of the most supine surrenders by United in living memory. The scoreline only ended 2-0 but United had more attempts on target at their own goal than City's.
That was Solskjaer's penultimate match as United manager and Pep Guardiola was asked if he was disappointed City did not win by a greater margin. "No, it's okay." Translation: Ole in. City fans chanted "Five more years".