Grealish scored his first Premier League goal in 16 months after a second-minute opener in the 2-0 win against the Foxes at the Etihad Stadium. After the final whistle, he spoke to BBC Sport about how he dedicates the goal to his younger brother Keelan.
"My little brother passed away 25 years ago today," he said. "This day is hard on the family.
"My mum and dad were here, so to score and to win was brilliant."
Grealish was four years of age when his brother Keelan died in April 2000, aged just nine months due to Sudden Infant Death Syndrome. He later wrote on Instagram:
"With me always especially this day ... that was for you Keelan."
Manager Pep Guardiola sent an emotional message to Grealish and expressed how tough it must be for his family.
"Jack is an incredible human being," said Guardiola. "He is incredibly generous.
"I didn't know that and I can't imagine how tough it can be with mum and dad and sister. It is good they remember him, this day. I am sure they remember him every single day. But it is good to score."