The 19-year-old midfielder recently signed a new contract with Aston Villa and the former Premier League striker is a big fan of his ability.
And Collymore, now a pundit with radio station talkSPORT, feels Grealish can go very far if he keeps his head down and learns from the likes of team-mate Fabian Delph and Villa assistant manager Roy Keane.
"Young Jack Grealish has a wonderful range of skills but he also has a real engine and tenacity. A new four-year deal at Aston Villa is designed to stave off interested from bigger clubs," Collymore wrote in his latest Bleacher Report column.
"Grealish could do with taking a leaf out of Raheem Sterling's book - get his head down, play more games and keep progressing. There are few better than Villa's assistant manager Roy Keane to get free advice from. He should lean on that as much as possible.
"Grealish can be special. He can play as an attacking midfielder, a holder or in the wide positions. All I'd say is stay at Villa, learn your craft and glean everything you can from the experienced players in the squad - the likes of Fabian Delph, for example.
"In 18 months, if he gets things right, Grealish will undoubtedly be a big target for the biggest clubs."
The Villans travel to Everton this Saturday, where kick-off at Goodison Park is at 3pm.