There were also wins for Aston Villa and Borussia Dortmund on the first night of action in this season’s league phase, as the opening matchday spreads across three nights.
Record 15-time European champions Real have brought back Mourinho for a second spell in charge, and his first game back in the competition came against the side he led to Champions League glory in 2010.
Madrid were two goals ahead midway through the first half at the Bernabeu thanks to two gifts from the Inter defence, with Yann Bisseck at fault as Kylian Mbappe opened the scoring on his 99th appearance in the competition.
Mbappe has now scored 71 Champions League goals, equalling the tally of Real legend Raul.
The home side doubled their lead when Inter goalkeeper Josep Martinez tried to turn away from Fede Valverde inside his own six-yard box only for the Uruguayan to tackle him and score.
Carlos Augusto pulled one back for Inter, but Real held on for the victory.
“It was a crazy game,” Mourinho told broadcaster Movistar. “A game that finished 2-1 could have finished 7-6 without any problems.”
Enzo Maresca’s City won 2-0 away to Portuguese champions Porto thanks to a second-half brace by Haaland, the first coming two minutes after the restart when he headed in Enzo Fernandez’s cross.
Haaland sealed the points in stoppage time and has now scored an astonishing 59 goals in 59 appearances in the Champions League.
“Erling Haaland is an animal. He is a beast, so every time he is on the pitch, I’m going to look for him, and hopefully give him many more assists,” Fernandez told Amazon Prime.
It was a fourth straight victory in all competitions for City, Champions League winners in 2023, whose next European game will be at home to title-holders Paris Saint-Germain. (AFP)