Romelu Lukaku started his second stint at Inter Milan with a bang by scoring a brilliant header two minutes into the 2-1 win at promoted Lecce.
However, Inter had to wait until Denzel Dumfries scored five minutes into added time to secure the victory in their first Serie A game of the season on Saturday.
"The team believed [in a win] until the end and this is the most important thing of the evening," said Inter coach Simone Inzaghi.
Belgian striker Lukaku, who was instrumental in Inter's title-winning 2020-21 campaign, returned to the club on a season-long loan from Chelsea less than a year after becoming the Premier League club's record signing.
Lukaku smashed the ball into the net after Matteo Darmian deflected a superb cross from defender Federico Dimarco.
Forward Assan Ceesay, however, made a fool out of Inter's defence by skilfully scoring an equaliser for Lecce in the 48th minute from a tight angle.
While Inter dominated possession, they spurned a host of chances throughout the game. Inzaghi brought on strikers Milan Skriniar and Edin Dzeko in the second half to change formation to a more offensive 4-2-4 from a defensive 3-5-2.
"We closed the game with all of our forwards on the pitch, the guys did well in believing [in a win] but the win should have been brought home sooner," Inzaghi added.
Inter host Spezia next Saturday while Lecce travel to Sassuolo on the same day.