Stefano Sensi's goal was the difference as Inter retained their 100 per cent record in Serie A by comfortably beating 10-man Udinese 1-0 on Alexis Sanchez's debut at San Siro.
A nine-minute spell before half-time proved decisive as Rodrigo de Paul was shown a red card for striking Antonio Candreva on the head following the intervention of VAR and Sensi nodded Inter ahead.
Romelu Lukaku endured a disappointing outing and made way for Lautaro Martinez in the 65th minute, before Sanchez replaced Matteo Politano to make his first appearance for the Nerazzurri against one of the forward's former clubs.
While Inter were unable add to their tally, they had already done enough to pick up a third straight win under Antonio Conte and move two points clear of Juventus at the top of the table.
Politano went close to putting Inter ahead in the fourth minute when his low drive from 25 yards struck the outside of the post.
Sensi saw a fine volley from the edge of the box pushed aside by Udinese goalkeeper Juan Musso, before Walace was kept out by Samir Handanovic at the other end.
Udinese were reduced to 10 men after 35 minutes when De Paul was shown a red card after referee Maurizio Mariani reviewed footage of his retaliation to Candreva appearing to touch his face.
Inter took advantage a minute before half-time, Sensi getting across Rodrigo Becao and heading a fine delivery from Diego Godin – making his first start since joining from Atletico Madrid – in off the underside of the crossbar.
Kevin Lasagna overpowered Godin but was thwarted by Handanovic, before Musso denied Politano and Roberto Gagliardini – a half-time replacement for Nicolo Barella – before the hour mark.
After Musso kept out a Sensi free-kick, an awkward fall for Politano paved the way for Sanchez to enter the fray to a great ovation with 10 minutes remaining.
Sanchez went close to marking his debut with a goal when Candreva's square pass fell to him in the six-yard box, but a scrambling Musso kept him at bay and Inter coasted to the final whistle.
What does it mean? Advantage Inter
With Juventus held to a 0-0 draw at Fiorentina earlier on Saturday, Inter opened up a gap over the reigning champions at the top of the table.
There is still a long way to go, but they are the only team to possess a 100 per cent record after playing three matches, though Torino could join them by beating Lecce on Monday.
Lukaku and Sanchez were the headline arrivals at San Siro this season but Sensi continued to show he is a valuable addition. The midfielder, on loan from Sassuolo, provided great support to the strikers and took his goal brilliantly.
Lukaku off the boil
After scoring in each of his first two matches and finding the net for Belgium during the international break, Lukaku failed to get into the action in Milan. He had no shots, created no chances and had a passing accuracy of 61.1 per cent in a disappointing outing.
Inter will be in Champions League action at home to Slavia Prague on Tuesday, while Udinese are not in action until the visit of Brescia next Saturday.