Bolton, who won the competition in 2023, raced into an early lead against Man City with goals from Sam Dalby, John McAtee and Aaron Morley.
There was no response from City as the League One side held on for a comfortable win.
Kamarai Swyer’s first goal for Northampton set them on their way to a 3-0 win over Chelsea. Swyer finished after good play by Michael Jacobs, making his second debut for his hometown club.
Jacobs then curled in a beauty before Elliot List was tripped and took the resulting penalty for his first goal for the Cobblers.
Plymouth – relegated from the Championship last season – handed the biggest defeat of the night to Tottenham Under-21s.
Mathias Ross Jensen took just five minutes to open the scoring and a Tegan Finn double was added to by Aribim Pepple, Owen Oseni and Seb Campbell in a 6-2 thrashing.
