Debutant striker Fousseni Diabate and Kelechi Iheanacho both scored twice as Leicester outclassed League One Peterborough to reach the FA Cup fifth round.
Diabate – signed from French side Gazelec Ajaccio – toe-poked in and Iheanacho guided the ball into the corner to put the visitors in control.
Ex-Manchester City forward Iheanacho volleyed home Christian Fuchs’ cross for a 3-0 half-time lead.
Posh improved after the break, pulling one back through Andrew Hughes, but Malian Diabate and substitute Wilfred Ndidi struck late on for the Foxes.
Premier League Leicester had Jamie Vardy and Riyad Mahrez on the bench but did not need to call on either, while Shinji Okazaki was left out of the squad altogether,
A side showing 10 changes proved more than strong enough as the Foxes’ fringe forwards thrived.
Demarai Gray and academy product Harvey Barnes played their part but it was Diabate and Nigerian Iheanacho who did the damage.
Diabate was lively throughout and slotted effortlessly into a fluid front four, while his strike partner now has braces in consecutive FA Cup ties after also scoring twice in Leicester’s replay win over Fleetwood in the third round.
Iheanacho is yet to score a league goal since his £25m summer move but has scored nine FA Cup goals in nine ties since January 2016 – more than anyone else.
While Manchester United boss Jose Mourinho marked his 100th game in charge in style on Friday with a 4-0 win in Yeovil, Peterborough manager Grant McCann could not follow suit as he reached the same milestone.
The storyline was there – the former Northern Ireland international had scored the winner for Posh the last time the sides met in 2013 – but a slow start took the tie beyond them.
While the 2015-16 Premier League champions were good, the hosts’ Chris Forrester gifted possession for Iheanacho to calmly slot in to make it 2-0.
However, Jack Marriott, Danny Lloyd and Marcus Maddison showed the attacking flair they are capable of in the second half and Hughes’ goal on the turn was the first Leicester have conceded in six games.
Peterborough now turn their attention to a League One play-off battle, with them four points behind sixth-placed Rotherham going into Saturday’s 15:00 GMT matches.
A run of only five defeats in 23 games in all competitions, coming into this tie, suggests they could yet achieve promotion back to the second tier.