Inter coast past Sampdoria as Mourinho watches from stands
Danilo D'Ambrosio, Joao Miranda, and Mauro Icardi scored to send Inter to only its fourth win of the year.
Inter moved to a point behind Fiorentina, which visits Atalanta on Sunday. Roma, which is a point behind Inter, hosts Palermo.
Former Inter coach Mourinho was at San Siro to watch his old team for the first time since leading the Nerazzurri to the treble in 2010. He was roundly cheered by the fans, while there was also a halftime choreography dedicated to him, with giant images of the three trophies and the words "For every day, every instant, every moment ... thank you forever Jose"
Former star Ronaldo did not get as warm a reception and there was even a banner criticizing the former Brazil striker, who departed to Real Madrid in 2002 before joining Inter's fierce rival AC Milan.
Earlier, bottom club Hellas Verona beat Chievo Verona 3-1 in the Derby della Scala for only its second win all season.
Sampdoria dominated the opening stages but Inter took the lead when Jeison Murillo headed on a corner for the unmarked D'Ambrosio to volley in at the back post.
D'Ambrosio almost went from hero to villain 15 minutes later when he blocked a Joaquin Correa shot with his arm but the referee waved away Samp's strong penalty appeals.
Joao Miranda's headed Inter 2-0 up after halftime, with goal-line technology — which has been introduced this season — proving Emiliano Viviano's save was too late to keep the ball out.
Icardi rounded off the victory, sprinting clear from just inside his own half before sending a low shot into the bottom right corner.
Fabio Quagliarella netted a consolation for Samp in stoppage time with his first goal since returning to the club on transfer deadline day.
In Verona, Artur Ionita sealed the home side's win in stoppage time, curling a spectacular effort into the top left corner.
Verona took the lead after it was awarded a penalty for a Nicolas Spolli foul on Luca Toni. Toni saw his spot kick saved but tucked the rebound into the other corner.
The hosts doubled their lead shortly before the hour, when Giampaolo Pazzini's low effort from a Mohamed Fares cross was deflected into the bottom right corner.
Sergio Pellissier got Chievo back into the game by converting a dubious penalty after Vangelis Moras was sent off for a second yellow card following a tussle with Roberto Inglese.
Chievo was also reduced to 10 men eight minutes later when Spolli was dismissed for a second booking.
Verona remained bottom, seven points below 17th-place Sampdoria.