That said, Sir Alex is hopeful that a new arrival in the Chelsea hot-seat bodes well as they welcome title rivals Manchester City to Stamford Bridge on Sunday.
"Benitez has been trying to get a job for a long time," he added. "I hope he is lucky on Sunday too! It happens time and time again when a new manager comes in they win their first few games. We’ve seen it before, it’s a strange thing how it happens. Sometimes you wonder if it encourages chairmen at football clubs to make changes because they think if we get a new manager we’ll win the next two or three games. History tells you that but you never know."