Reserve goalkeeper Frey said he would offer advice to French first choice Gregory Coupet ahead of their opening Euro 2008 Group C game in Zurich.
"I'll give Greg a few tips," said Frey. "He (Mutu) is technically very strong and capable of making a difference at any moment.
Mutu hit six goals in qualifying and is a proven quality finisher but he does have his weaknesses, added Frey.
"If you manage to neutralise him he can lose his nerve and become predictable," said the keeper.
"He's a good goalkeeper who decided to go back to Romania," said Frey. "From the images I've seen he's in great form and should have a good tournament."
"I've met him many times on the pitches of Serie A and he's an excellent player (in defence or midfield)," said the keeper. "He's a skilful player and extremely dangerous from set pieces. We'll have to keep an eye on him."