Bulgaria star Petrov said: "Other players who are trying to get into the English national team should learn from Gareth. He showed such determination as he was fighting with two of the best midfield players in the world in Lampard and Gerrard.
"But now you can say Gareth is the main guy in the England midfield, which is impressive as it's hard to get there but even harder to keep your place.
"England have outstanding midfield players, but it seems Gareth has been Capello's best because he's always in the team. Gareth has had to wait his turn but now he's determined to keep his place. He never gave up and it's great seeing someone going away with their national team with a smile on their face.
"He missed international football for quite a long time but now he comes back stronger with more confidence and he looks like he's never been out of it.
"He's playing well and pulling strings there and I think the other England players respect him."
Barry, who made his England debut in 2000, almost quit Villa this summer for Liverpool as the Anfield club tabled four bids for him.
But manager Martin O'Neill refused to cash in on his biggest star and Petrov now believes Villa can break into the top four with Barry pulling the strings.
"We're all happy Gareth is still in our team and not in someone else's causing us trouble," added Petrov ahead of third-placed Villa's trip to league leaders Chelsea.