Phil Foden scored his first Manchester City goal with Gabriel Jesus and Riyad Mahrez on target either side of half-time as the holders eased into the EFL Cup last 16 with a 3-0 victory at Oxford United.
City named a strong side for the third-round clash including captain Vincent Kompany and Nicolas Otamendi in defence, while John Stones operated in an unfamiliar role in front of the back line and there were starts for youngsters Foden and Brahim Diaz.
Brazil striker Jesus recorded his second of the season with a close-range header, and thereafter City's progression was not in doubt, with Foden brilliantly setting up Mahrez for a late second.
And teenager Foden opened his account for the club with an arrowed finish in added time to make a case for more regular selection under Guardiola this season.
Jesus thought he had struck in the 19th minute but the offside flag cut short his celebrations, although the striker would not be denied by the officials when he opened the scoring.
After referee Roger East played a good advantage, Foden swung a superb crossfield pass out to Diaz, whose shot rebounded up for Jesus to stoop and head home from a few yards out.
Danilo, making his first appearance of the season, rifled a long-range drive narrowly wide of the angle in the 50th minute as City sought a second goal.
Foden missed a sitter from a Danilo cross but made amends with a brilliant pass that sent Mahrez clear on the break to score with a powerful strike with 12 minutes left.
And Foden ensured City's passage in the 92nd minute, rounding off a star performance in style with the Premier League champions rarely needing to get out of first gear to start their EFL Cup defence with a win.
What does it mean: City challenging on four fronts
City were not expected to be stretched against League One opposition and the match went mostly to plan, with debutant teenage goalkeeper Arijanet Muric mostly untested. Foden and Diaz were both involved in the opening goal and Oleksandr Zinchenko was bright at left-back. Guardiola has plenty of young talent and the EFL Cup may be the ideal proving ground if City are to target a quadruple.
Foden meets expectations
An awful lot is demanded of Foden and it is easy to forget that although Guardiola has touted him for a senior England call-up, he is only 18. This was the sort of match a talent as prodigious as Foden should have dominated and the wonderful pass to fellow youngster Diaz that created the opening goal showed what he could do. Foden occasionally operated on the fringes of the contest, but another superb ball created the second goal for Mahrez and he got the goal he deserved at the end. His ability is not in doubt.
Nervy moments for Muric
Recalled from NAC Breda after Claudio Bravo's injury, this was a first City appearance for goalkeeper Muric - and it showed. He appeared unsettled when Oxford delivered long throws into his box and with the third-tier side unable to create chances he could not build any confidence by making saves. Pre-match talk of Muric being Ederson mk II may be premature.
City host Brighton and Hove Albion in the Premier League on Saturday, while it is back to League One action for Oxford, who are away to AFC Wimbledon on the same day.