Internazionale chalked up their first victory of the season and made it a winning home debut for coach Jose Mourinho, but they were made to work hard by opponents Catania.
Gianvito Plasmati stunned the San Siro by putting Catania ahead in the 42nd minute, but a deflected goal from Ricardo Quaresma restored parity a minute later.
Inter then lost Sulley Muntari to a red card just before the break, but a disputable own goal from Christian Terlizzi early in the second half gave Inter the spoils and provisional place at the top of the table ahead of Sunday's matches.
Former Inter legend Walter Zenga was given a warm welcome by everybody inside the San Siro as he entered the field with his Catania team.
He was awarded a replica Inter shirt with the number 473 - corresponding to the number of appearances he made as the Nerazzurri's goalkeeper - by Inter captain Javier Zanetti before the game.
But that was as far as Inter's hospitality extended and as soon as the whistle went, they set about breaking the Sicilians down.
The Nerrazzuri practically camped in the Catania half for the first 45 minutes, but they could not break through a well-drilled defense.
The closest they came was from a Quaresma cross which Muntari reached in the 31st minute. His shot deflected off Terlizzi to make the save even more difficult for Albano Bizzarri.
Catania only made it across the halfway line a handful of times in the first half, but still took the lead with their first real chance in the 42nd minute.
Plasmati rose above Muntari to reach Giacomo Tedesco's cross and head the ball past Julio Cesar in the Inter goal.
Their lead lasted less than a minute though before a touch of fortune allowed the home side to level.
Quaresma's cross took a deflection off Giuseppe Mascara to sneak inside a wrong-footed Bizzarri's near post and mark the Portuguese midfielder's debut with a goal.
There was further drama before the referee could bring the first half to its end as he brandished a red card at Muntari for violent conduct when the former Udinese and Portsmouth midfielder was seen to swing an arm in the face of Tedesco.
The red card also sparked a heated confrontation between opposing players as they left the field at the interval, although no further action was taken by the referee.
Within three minutes of the restart, Inter went ahead with a controversial goal.
Terlizzi flicked a long Inter throw-in onto the inside of his own post with his head and Bizzarri collected the rebound which the linesman said had crossed the goal line.
The blow meant Catania had to change their tactics and demolish their defensive wall in favor of a more attacking style.
This put Inter onto the back foot and, while the home side had dominated the first half, it was the visitors who enjoyed the lion's share of possession in the second.
They were unable to break down the massed ranks of Inter players and, as they were forced to take risks, they left opportunities open to Inter.
Nicolas Burdisso missed a volley from point-blank range for the hosts and Maicon dribbled his way through before firing wide.
In the closing stages of the game, Zlatan Ibrahimovic missed a one-on-one with Bizzarri before he made claims for a goal when Bizzarri made another save on the goal line, although the linesman this time ruled in the Catania keeper's favor.
