The Italy forward moved to the Spanish champions on a three-year deal on transfer deadline, as Torino's attempts to keep hold of the 27-year-old proved in vain.
Atleti midfielder Tiago has warned supporters that Cerci may not make an instant impact, however, as he and the team need to learn each other's strengths.
"He must adapt quickly because we are competing," Tiago told Mundo Deportivo.
"We must adapt to his style of play and he our style. It will take a few weeks to see the best Cerci, but this is football. He brings quality and competence in attack. He can only improve."
Atleti have lost Diego Costa and David Villa from last season's La Liga winning side, but Tiago wants the team to quickly move on from their departures and improve in attack.
"It [Costa and Villa leaving] has changed our attack," he added. "Two very important players left that have played a lot.
"You have to adapt because there are players with different characteristics than we had before. We defend well, we know what to do, but the attack must improve because we rely heavily on that facet."
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