Another scintillating display – troubled only by Stoke hitting the woodwork twice in the first 45 – saw Carsley’s side tease and torment their counterparts, particularly in the second half, carving open the opposition defence with ease.
Diaz did well to beat his man before firing across the box, but it somehow evaded Jadon Sancho.
Three minutes later though, the deadlock was broken with the first piece of individual brilliance.
Diaz again demonstrated why he is so highly rated, weaving his way through the Stoke defence before slotting calmly into the corner.
Inspired, the Blues went in search of a second and almost netted it but Luke Bolton blazed over a backpost volley.
Foden also tried his luck with a low effort, which skewed wide, before the Potters responded with a period of pressure.
Former Blue Tyrese Campbell – top scorer in the competition with seven goals in four games – was unfortunate to strike the post, having done well to create space and unleash a shot from a narrow angle.
At the other end, Sancho’s driven free-kick flew just wide before Stoke struck the woodwork again, when Jordan Greenidge rattled the bar with a fierce shot.
City capitalised on their fortune with another excellent individual goal – this one courtesy of Foden, who turned his man, drove into the penalty area and wrong-footed Mate Deczki.
With a two-goal advantage, the Blues looked to be heading into the break with a comfortable lead – but there was still time to extend it, as Luke Bolton regained possession in a dangerous area and crossed for Nmecha to head in.
City continued where they left off after the restart and added a third when Duhaney marched his way through the Potters’ backline and finished well.
The forward completed his hat-trick with just over ten minutes of normal time remaining, cutting inside on the edge of the area and rocketing into the top corner to cap an excellent individual and team display.