Grealish enjoyed a wonderful breakthrough season last year, when he became one of Villa’s most important players.
However, the 20-year-old has failed to build on that campaign this time around, and his role has diminished in importance.
Collymore is now worried that the youngster’s attitude is poor, and he has suggested that Grealish only needs to look at Leicester City’s Marc Albrighton to see how far he could progress.
“How about the comparison between two of our own, Marc Albrighton and Jack Grealish,” Collymore said.
“I love both, have chatted to both, but where Marc moved on, grafted his way into the Leicester team and will win a winners medal, rumours persist of Jack the lad on the town in Brum, surrounded by the hangers ons.
“That should worry every Villa fan as this lad has genuine quality, is twice the talent of Albrighton, yet may have so been infected by the ‘couldn’t give a s***’ attitude of the seniors that it’s only going to be a very strong manager that gets him back on track.”
Albrighton was released by Villa back in 2014, after being deemed surplus to requirements.
Albrighton has gone on to prove his class, however, by playing a key role in Leicester’s push for the title this season.
Grealish, meanwhile, has failed to make much of an impact during Villa’s terrible season.
The Claret and Blues have managed to win just three matches this term, with Grealish making just 19 appearances in all competitions.
Grealish’s future at Villa Park is now uncertain, following the club’s relegation to the Championship.