Capello saw Milner turn in another fine display, despite scoring an own goal, during Saturday's 2-2 home draw with Wolves.
Petrov said: "James was a wide player, but he has always preferred to play in the middle. He has been doing really well.
"His energy is amazing and he has helped the team a lot. He can play anywhere.
"He has been brilliant - and if he continues to progress like that, he will be the star of the World Cup.
"He has both the ability and the attitude to make a real impact.
"He has scored 10 goals from midfield, which is really good. He has the licence to get forward and he shows great composure in front of goal.
"His work-rate is great, as well. He deserves everything he gets."
Villa winger Ashley Young echoed Petrov's sentiments about Milner, who was signed from Newcastle in 2008 for a club record £12 million.
He said: "Regardless of what position James has played, he's just been tremendous all season.
"He's definitely a contender to be player of the season already. He has been fantastic for us and the way he goes about his job is just exceptional.
"We've got quality players in the middle there like James and Stiliyan but then we've got the likes of Steve Sidwell and Fabian Delph too.
"We've got competition but Milly has been brilliant for us, just brilliant."
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