City star Grealish linked up with Sky Sports pundits Keane, Gary Neville, Jamie Redknapp and Micah Richards for a post-match interview while his team-mates and fans celebrated on the pitch.
The legendary United captain, who won seven Prem titles during his celebrated career, was asked what advice he had for the 26-year-old, who just won the league for the first time.
Keane said: “Keep off the top shelf, stick with beer.”
Grealish and the rest of the panel were left in stitches after that hilarious tip.
But the forward insists he is ready to wholeheartedly celebrate the greatest moment of his career.
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Grealish responded: “Not for the next three nights. No chance.”
City came from behind against Aston Villa to seal the title at the Etihad and end Liverpool’s hopes of an unprecedented Quadruple.
Legendary Reds captain and Villa manager Steven Gerrard saw his team pick up a two-goal lead with Matty Cash and Philippe Coutinho.
But Pep Guardiola’s men fought back with three goals in just five minutes thanks to Rodri’s strike and Ilkay Gundogan’s brace.
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United great Keane looked visibly unimpressed after watching his former rivals clinch their fourth title in five years, while ex-City ace Richards was having the time of his life.
But that didn’t stop the legendary midfielder from praising the Manchester giants’ incredible achievement.
Keane said: “The bottom line is, the challenge City faced today was in front of them, Aston Villa.
“You know you’ve got to score three goals to win the title. That’s huge pressure. You’ve got to get the ball running.
“Credit to City. Them and Liverpool are the hardest working teams.”