The 24-year-old went toe-to-toe with a Chelsea midfield which consisted of Willian, Ramires and Nemanja Matic on Saturday.
And he came out on top as he scored a memorable winning goal against Jose Mourinho's Premier League leaders to seal a shock win at Villa Park.
The Scot says the former Leeds United star, who has earned rave reviews this season, has put his injury problems behind him and he can now develop into top class player.
"He's been excellent over the course of the 18 months I've been here," Lambert told the Birmingham Mail.
"What sort of player can he develop into? You've seen what he's got, there's massive potential there to be a really top player and if he keeps his feet on the ground, keeps learning, keeps doing what he's doing then we'll see where he goes.
"He's got great energy. Sometimes he wants to hold on to it too long. That will come with more experience, he'll release the ball at the right times.
"Fabian has been playing for the majority of the season and he's been excellent for us.
"He has ups and downs, like everybody else, but over the piece he's been consistent for us. He's been training most days, been fit for most games and if he gets goals from the middle of the pitch it will certainly keep him going, that's for sure."