Liam Kinsella’s superb strike helped Walsall edge past League One rivals Sunderland and set up an FA Cup third-round trip to Championship side Bolton.
The Republic of Ireland Under-21 international notched just his second career goal seven minutes after the restart when he drilled a super right-footed drive into the corner.
Josh Gordon and Josh Ginnelly also went close for the visitors, who are through to the third round for only the second time in ten years.
It was the third meeting between Walsall and Sunderland in 18 days, with the previous two both finishing in draws.
And there was nothing between the sides in a fairly flat opening quarter of an hour at a sparsely-populated Stadium of Light.
Walsall threatened first as Kieron Morris cut infield and steered a left-footed 20-yard drive into the side-netting.
Sunderland responded instantly, with Duncan Watmore seeing a shot from a narrow angle blocked by a sliding Russell Martin and having the rebound saved by the legs of keeper Liam Roberts.
Dean Keates’ men were more than holding their own against the League One title chasers and wasted a promising counter-attacking opportunity midway through the half.
Kieron Morris’ sumptuous sweeping pass set Josh Ginnelly racing clear but the Wearsiders got men back to snuff out the danger.
After a slight lull, the visitors fashioned a glorious chance to go ahead six minutes before the break.
Josh Gordon released Morgan Ferrier down the left, with the forward brushing off the challenge of Tom Flanagan and advancing into the box.
He squared to Gordon – who looked certain to score six yards out – but Black Cats keeper Jon McLaughlin did superbly to smother his close-range attempt.
Another opportunity came and went for the Saddlers as Ginnelly pulled a right-footed shot wide of the near post.
Jack Ross’ high-flying hosts were surprisingly subdued in the first half but went close on the stroke of half-time when Max Power drilled a crisp low drive inches past the left-hand upright.
The north-east club started the second period brighter, Watmore turning on the edge of the box before firing off target.
But it was the Saddlers who broke the deadlock seven minutes after the restart – from a very unlikely source.
Receiving possession 25 yards out, Kinsella steadied himself before fizzing an unerring right-footed strike beyond a helpless McLaughlin for just his second career goal.
His previous goal came in a 2-0 win over Burton in October 2015 – against the same keeper!
The response from Sunderland was muted to say the least.
Russell Martin’s wayward pass presented Watmore with an opening, but the centre-back made amends by blocking his curling shot.
Luke O’Nien also headed a corner wide and Bryan Oviedo sent a free-kick wide of the far post, as the Black Cats struggled to muster a meaningful chance.
Sunderland team: McLaughlin; O’Nien, Baldwin, Flanagan, Oviedo; Honeyman, Power, McGeouch (Cattermole 58’); Maguire, Watmore (Mumba 78’), Sinclair (Maja 58’).
Subs not used: Ruiter, Loovens, Ozturk, James.
Saddlers team (4-4-2): L Roberts; Devlin, Martin, Guthrie, Leahy; Morris, Osbourne, Kinsella, Ginnelly; Gordon, Ferrier.
Subs not used: Dunn, Johnson, Edwards, Bates, Ronan, Kouhyar, Parker.
Attendance: 8,212 (201 Saddlers fans).