The Ivorian was the 53-year-old’s first signing of the summer, joining from Villarreal for £30m in June.
After a hugely impressive pre-season, Bailly put on a defensive masterclass alongside Daley Blind, acting as a effervescent battering ram and dealing expertly with Leicester’s swift counter-attacks.
Speaking after Manchester United’s 2-1 win, the Portuguese was quick to praise the 22-year-old.
“Eric (Bailly) is working since day one,” said Mourinho.
“He started the pre-season with us, he played matches, he’s fit so I knew that with him it’s just a question of his personality allowing him this big move from Villarreal to Man United to Wembley. It was just that.
“He was super comfortable so no doubt that he’s a man for us.”
For a youngster coming from La Liga, going up against the Premier League champions, hallmarked today by the notoriously rambunctious trio of Jamie Vardy, Shinji Okasaki and Ahmed Musa in front of 90,000 people, this afternoon provided a stern test for the Ivorian.
Much to the delight of supporters, Bailly passed with flying colours. It was a performance hallmarked by an almost dangerous level of aggression and power, which saw the Ivorian flatten various players, receive a yellow card and lose a boot. A bright and entertaining future certainly lies ahead for this kamikaze-esque diamond at the back.