Roy Keane fired a sly dig at Manchester City's perilous title charge following Saturday's 2-1 derby defeat to Manchester United at the Etihad.
The result leaves City's hopes of claiming a third successive title hanging by a threat, with the champions now 14 points behind leaders Liverpool.
Speaking on Sky Sports News after the game, Keane said: "To win the league championship, you've got to go and earn it.
"For City, they've won it for the last couple of years - fantastic - but we all know how difficult it is to win three years in a row. Not many teams do that."
The former United captain was alluding to the fact that his former club remains the last team to win the Premier League three times in a row between 2006 and 2009.body check tags ::