By ESPNSTAR.com staff
Berg still follows the fortunes of United closely and this season he has grown frustrated by the poor finishing of United's strikers.
He believes that Kagawa, who joined United from Borussia Dortmund in the summer, has been a real positive influence on Sir Alex Ferguson's team in terms of creating chances for team-mates such as Robin van Persie and Danny Welbeck.
The 23-year-old Japan international was one of few United players who impressed in Wednesday's slim 1-0 UEFA Champions League win over Galatasaray at Old Trafford.
"I was very impressed with Kagawa [against Galatasaray]," Berg told talkSPORT.
"He looks a top player and is a real bundle of energy.
"His positional play in that role gives Man United something extra. They've not had someone in that role before.
"The only thing missing is someone to score all the chances he makes.
"Kagawa gives Man United an extra dimension. His positional sense is excellent both offensively and defensively. He's always available to get on the ball. It's easy for Paul Scholes and Michael Carrick to find him."
United's strikers will need to have their shooting boots on when the Premier League resumes this weekend. The Red Devils make the short trip to Anfield to face arch rivals Liverpool in what is expected to be a closely fought game.