Wanderers, three up after only 17 minutes, through Jay-Jay Okocha, Kevin Nolan and Stelios Giannakopoulos had the Cardiff hotel booked for the final.
Yet two goals from Juan Pablo Angel either side of half time hauled Villa back into the game.
That signalled time for Okocha to open his box of magic tricks to taunt and tease the Villa defence and Bruno N'Gotty grabbed a fourth before Okocha crowned his show with a stunning free-kick in the 80th minute.
The second leg looks a tremendous prospect but Villa will be relieved to know that Okocha will be missing - he's away captaining Nigeria in the African Nations Cup.
Villa had hardly warmed up when they found themselves two goals down.
A foul on Kevin Nolan by J Lloyd Samuel in the second minute gave Wanderers a well-positioned free-kick just outside the Villa area.
With Sunday's embarrassment against Arsenal still fresh in their minds, Villa quickly dispatched a defender to stand over the ball to avoid any repetition.
Yet that hardly registered with Okocha, who once the way was clear, curled the free-kick around the edge of the wall and just inside the post.
Six minutes later Wanderers doubled the lead as Nolan raced on to Kevin Davies' flicked header from Jussi Jaaskelainen's clearance before firing the ball past Thomas Sorensen.
Villa could hardly believe it and they were stunned again in the 17th minute when Greek international Stelios fired an overhead kick into the net following a Davies header.
The pace was frantic and ironically Villa had produced as much attacking play as the home side.
Finally they managed to make their mark on the game in the 20th minute, although when Angel put the ball over Jaaskelainen and into the far corner from such an acute angle, it was difficult to judge whether it was an intended shot or cross.
A second could easily have followed but Jaaskelainen just managed to get a fingertip to the ball to divert Gareth Barry's cross away from the incoming Darius Vassell.
And it took a tremendous block by the Wanderers keeper to keep out a close-range shot by Barry on the stroke of half-time.
It was hard to imagine the game continuing in such a fashion after the break but it did, both sides throwing caution to the wind in breathless pursuit of more goals.
And when the next score came, ten minutes into the half, it was Villa's turn to gain the early advantage, Angel snapping up the rebound to fire in his second goal after Jaaskelainen had knocked away Gavin McCann's shot with Wanderers appealing in vain for an offside decision.
That sparked the home side to push forward again and when Youri Djorkaeff delivered a 74th minute corner, his fellow Frenchman N'Gotty powered a six-yard header past Sorensen.
And it didn't finish there, Okocha delivering his second goal in the 80th minute with a tremendous free-kick that screamed past the stranded Villa keeper.