The Italian manager admitted that he has a big call to make regarding the Algerian's involvement against Liverpool on Saturday but quipped that Slimani has just one duty in the game at Anfield if he's picked to play.
He said of the £28million signing from Sporting Lisbon: "It is a big call. But he is good – he only has to score goals!
"He is ready. He has played all the matches with Sporting Lisbon and he is ready to play with us. We brought him here because we believe in his ability.
"The Premier League is different from the Portuguese League but he is a very interesting player.
"He is similar to Ulloa and now I have two big boys up front so I have a very good choice.
"Slimani cost a lot of money but if you see the market, it was a crazy market! I think as a goalscorer he cost less than others. He was a good buy for us.
"If you want to improve and fight in every competition you have to spend money."