Francesco Totti netted a penalty midway through the first half after a foul on Daniele De Rossi by Michele Canini and Simone Perrotta doubled the lead in the second half after Juan's header was parried. Jeremy Menez scored a late third.
Totti's goal followed a spat earlier this month with coach Claudio Ranieri, who according to media reports has also clashed with Mirko Vucinic over the rotation of his strikers.
The Montenegro forward started on the bench after owner Rosella Sensi, who is being forced to sell the debt-ridden club in a long drawn-out process, said he was not for sale amid reported interest from Juventus.
Struggling Catania lost 2-0 at mid-table Parma in new coach Diego Simeone's first game in charge. The ex-Argentina and Inter Milan player, making his debut as a coach in Europe after winning two titles in his homeland, watched in frustration as ex-Juventus midfielders Antonio Candreva and Sebastian Giovinco scored after the break.
"There were good things and others less so," former tough-nut midfielder Simeone told reporters. "The first half was good and also at the start of the second we had chances."
Catania, who parted ways with coach Marco Giampaolo in the week, are 16th but could be dragged further towards trouble after Sunday's main programme of matches.
It was not a totally bad day for Sicily with Palermo, in seventh, scoring late through Cesare Bovo to beat second-bottom Brescia 1-0 and keep their European hopes burning.
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