The Saddlers produced a stunning performance to thrash League One leaders Sheffield United and make it a hat-trick of wins against the Blades this season.
Amadou Bakayoko fired the hosts into a fifth-minute lead, only for Jack O’Connell to head United level seven minutes later.
But Jon Whitney’s men ran riot after the break, with goals from Jason McCarthy, Joe Edwards and Erhun Oztumer securing a handsome, and thoroughly deserved, victory.
United, chasing a seventh straight win, almost went ahead inside four minutes when League One top scorer Billy Sharp crashed a fierce volley against the bar from Kieron Freeman’s cross.
The Saddlers broke forward immediately, Joe Edwards slipping in Bakayoko who confidently finished left-footed across Simon Moore for his third goal against the Blades this season.
But the home side’s lead didn’t last long.
A deep free-kick on the left was nodded back across goal by Wolves loanee Ethan Ebanks-Landell and headed in by Jack O’Connell from close range.
Florent Cuvelier, playing against his former club for the first time, looked to restore Walsall’s advantage straight away, unleashing a blistering 25-yard drive which whistled just over.
The game began to settle down after a pulsating opening quarter of an hour, with Chris Wilder’s Blades enjoying more of the ball and looking the more dangerous.
United captain Sharp twice went close, first firing straight at Neil Etheridge from inside the area before turning Freeman’s low cross narrowly wide from six yards.
The title favourites threatened again on the stroke of half-time, Caolan Lavery with a right-footed effort which Etheridge palmed behind.
Half-time: Walsall 1-1 Sheff Utd
The Saddlers started the second period brightly, with Bakayoko’s improvised overhead kick forcing Moore into a fine one-handed save and Oztumer firing off target after some neat build-up play.
And the home side went back in front just before the hour mark, McCarthy exchanging passes with Bakayoko before slotting past Moore at his near post.
With Walsall on top, it was very nearly 3-1 moments later as Edwards rounded Moore but saw his attempt deflected – possibly by a hand – over the bar.
But the Saddlers, and Edwards, weren’t to be denied midway through the second half, the ex-Colchester man firing low into the bottom corner after good work from Bakayoko.
Quite incredibly, Jon Whitney’s side then made it 4-1 with 14 minutes remaining, Oztumer converting a penalty after substitute George Dobson was brought down by Moore.
The Blades, who had lost only one of their previous 22 games, almost pulled one back but Etheridge made a super diving save to keep out Leon Clarke’s header from Mark Duffy’s cross.
Full-time: Walsall 4-1 Sheff Utd
Team (3-5-2): Etheridge; O’Connell, O’Connor, Preston; McCarthy, Chambers, Osbourne, Cuvelier (Dobson 74’), Edwards; Oztumer (Morris 88’), Bakayoko (Jackson 77’).
Subs not used: MacGillivray, Laird, Roberts, Makris.
Attendance: 6,899 (2,532 Sheff Utd supporters).