"That is why we bought him," declared Mancini.
"He is a young player who wants to do well. He can play on both the left and the right and he can also play behind the main striker. He can continue to grow and I think he can be a very important player for this club."
Johnson claimed the assist for Tevez's 19th goal of the season when he was brought down by Paul Robinson on the half hour.
Bolton boss Owen Coyle claimed it was a "soft" penalty. The tackle actually looked ridiculous given Robinson made no contact as he lunged in on an opponent who appeared to be heading over the by-line.
Adebayor sealed victory with a brilliant finish to a pass from another new boy in Patrick Vieira. At 33, it is felt by many Vieira's best days are behind him.
Yet the Frenchman bristles at such suggestions and reacted with a curt "am I that old?" when he was asked after the game whether he would need a rest on Wednesday.
Mancini can see Vieira's point and thinks the midfielder can follow his own example and play until he is 36.
"I played until I was 36 and I was still playing well," countered the Italian. "I won the Scudetto at that age, so I see no reason why Patrick can't carry on as well.
"First of all I hope he can play another 15 games for us in the league this season because his performances are going to be very important."
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