The two teams are preparing to meet in the first-leg of their Champions League round 16 tie.
Conceicao said, "It thrills me to be able to return to Rome and relive the unique moments I shared with the Lazio fans, but right now I'm only thinking about this game.
“Zaniolo? They have some very good players. Zaniolo's very important for how their attack functions.
“He has a lot of quality and we'll take him into consideration like everyone else because we work on the collective.
“He's a young lad of great value. Marcano? I coached him last year, he's a great professional and I don't know why he's not finding space in Italy.
“He has immense qualities and was fantastic last season."