The Aston Villa man has hailed the talent of his young colleague on the back of some eye-catching displays in recent weeks.
The youngster has impressed in recent weeks after being given an unexpected start in the 3-3 draw with QPR earlier in the season.
He has since become one of the first names on the team sheet, impressing in games against Tottenham, Liverpool, Manchester City and Everton - with his performance in the FA Cup semi-final against Brendan Rodger's side being a particular highlight.
Now, speaking ahead of this weekend’s clash with West Ham United, Westwood has said that the sky is the limit for the highly-rated starlet.
“Jack's talent is frightening,” he said.
“Just look at the way he picks the ball up and runs with it - he glides across the turf and goes past people for fun. If he adds a couple of goals to his game - which I am sure he will do - he can be whatever he wants to be in the game of football.”
Grealish has often been talked about with enthusiasm at Villa Park, with many expecting him to come good for a while, despite his young age.
However, he received limited opportunities under former manager Paul Lambert. The arrival of Tim Sherwood as the Scot's successor gave him his big break, with the former Tottenham manager having a history of developing young talent.
As far as Westwood is concerned, though, the young attacking midfielder deserves praise for taking his opportunity and expects him to develop into a top player if he continues how he has started.
"He's been handed his opportunity on match day and he's taken it,” he added.
"He's only 19. He will gain more and more of a knowhow of the game as he gets older - although he's got that in abundance now. He will be a real top player.”