The former Arsenal keeper claims that Grealish is just like Messi with a right foot.
The England international is having a superb season at the Villa Park, having scored six and provided 10 assists in the Premier League so far.
Martinez, who moved to Villa from Arsenal after spending 10 years at the Emirates Stadium, believes Grealish’s value and ability is comparable to the six-time Ballon d’Or winner.
“He [Grealish] is the most talented player I’ve ever seen,” the keeper told talkSPORT.
“He never gives the ball away. When I see Grealish running, it’s always a shot on target or a corner for us. He will drive past two or three players.
“I just see Messi with a right foot when he has the ball. You can’t get the ball off him. He’s the most talented English player and I’m surprised he hasn’t played more games for England.”
The 28-year-old added: “Messi is Messi, he’s the best ever. But in terms of training, when Jack has the ball, people don’t want to tackle him, they respect him, he can finish, he can chop, he can do everything.
“When I train with Messi for the national team, it’s the same. Nobody wants to touch him, he chops people, he treats players like cones. I see that with Jack here.
Emiliano himself is having a good debut season in Aston Villa as he has kept eleven clean sheets in 21 Premier League games.
