Roberto Mancini fears Sunderland's Adam Johnson could come back to haunt Manchester City as the winger prepares to return to Etihad Stadium.
Johnson, 25, is set to play in Saturday's Premier League clash after
leaving for the Black Cats in August.
Mancini said: "I am sure he will do well for Sunderland and go to another top team because he deserves this.
"I hope he can have a good game on Saturday because I like Adam, I think he is a really good player."
Johnson made 25 top-flight appearances as City won the Premier League title last season, but 15 of those came from the substitutes' bench.
Mancini admitted the England international became frustrated with his bit-part role and fully understands his decision to seek regular first-team action with Sunderland.
"He is a good guy and a good player," added Mancini. "I think Adam played well here.
"The problem was maybe that he didn't play always. For young players like him it is important to play every game.
"He wanted to play every game and here it was difficult, he decided to leave."
Shortly after his move to the Stadium of Light, Johnson admitted he felt "it was always going to be difficult" to break into Mancini's first-team plans after being
given little reassurance by the Italian over his role.
Ex-Middlesbrough trainee Johnson
joined City in a £7m deal in February 2010
and played 97 games, including 43 substitute appearances.
He has won 12 England caps, scoring two international goals.