Villa's young guns suffered a punishing defeat at Newport County despite leading twice against the newly-promoted League Two side.
Jack Grealish and Daniel O'Brien scored well-worked goals in a bright first-half display at Rodney Parade.
But ruthless Newport - who are less than a week away from kicking off their first Football Leauge campaign for 25 years - turned the tables after the break.
The hosts started brightly with Andy Sandell's left-foot drive clipping the bar after he got the better of Jordan Lyden on the left.
But Villa took the lead with a well-worked Grealish strike after 11 minutes.
Henry Cowans played an intelligent pass to the left flank and Grealish controlled well before moving towards goal and tucking a shot into the bottom corner.
Another excellent move - once again orchestrated by Cowans - allowed Daniel Johnson his first sight of goal but the Villa skipper curled his 18-yard effort just off target.
The equaliser arrived on 33 minutes when Sandell produced a dangerous cross from the left which was scrambled over the line from inside the six-yard box by Danny Crow.
It took just four minutes, though, for Villa to regain the lead. Wideman O'Brien caught everyone out by cutting in and driving a low shot to the near post which was too powerful for the outstretched leg of Stephens.
The Welsh outfit turned the game on its head after the break.
Substitute Andrew Hughes converted Max Porter's right-wing cutback to make it 2-2 on 57 minutes.
Three minutes later, Lee Minshull's close-range header was spilled by Villa keeper Brad Watkins as the hosts edged in front.
Andy Sandell's corner caused chaos in the Villa box, allowing Christian Jolley to force home the fourth just past the hour mark.
In the closing stages, Minshull controlled a cross on his thigh before volleying into the bottom corner for his second of the afternoon.
NEWPORT: Stephens, Pipe, Anthony, James, Yakubu, Sandell, Porter, Chapman, Minshull, Crow, Jolley. Subs: Jackson, Zebroski, Washington, Hughes, Doble, Bittner.
VILLA: Watkins, Lyden, Bateman, Webb, Kinsella, Cowans, Calder, O'Brien, Sellars, Johnson, Grealish. Subs: Wildin [for Kinsella, 75], Bannister, T Strain [for Sellars, 65].