Walsall booked an FA Cup third-round trip to former manager Dean Smith's Brentford after beating Chesterfield on penalties.
Chances were at a premium in a tense 120 minutes, with Kieron Morris going closest for the Saddlers when he rattled the bar.
In the shoot-out, Walsall converted all five spot-kicks, with Paul Downing scoring the winning penalty after Sam Morsy had fired over.
The Saddlers are in round three for the first time since 2008 and will now travel to Griffin Park on 9th January.
Walsall showed three changes from the side that drew 1-1 with Chesterfield in the initial second-round tie, ten days ago.
Anthony Forde, Sam Mantom and Andy Taylor came into a 3-5-2 formation, with Rico Henry, Milan Lalkovic and Kieron Morris dropping out.
The Saddlers started purposefully with Romaine Sawyers testing visiting keeper Tommy Lee with a well-struck low drive inside three minutes.
Jordan Cook was next to threaten when he carried the ball to the edge of the box before dragging a right-footed shot wide.
Despite dominating possession, Walsall were struggling to fashion clear-cut scoring opportunities, although Sawyers was causing problems.
The influential playmaker saw a 25-yard strike charged down by Ian Evatt and then stood up a delightful cross which just evaded Cook.
Chesterfield responded with Sam Morsy and Lee Novak each firing off target, while Evatt headed straight at home keeper Neil Etheridge.
Walsall came within inches of breaking the deadlock nine minutes before the break, when Anthony Forde’s free-kick deflected a whisker wide.
HALF-TIME: WALSALL 0-0 CHESTERFIELD
Forde threatened again shortly after the resumption, as his whipped cross eluded everyone and almost crept in at the far post.
Chesterfield were a greater threat in the second half.
Dieseruvwe’s header was held by Etheridge, before Novak’s lofted cross floated over the home keeper but dropped the wrong side of the post.
The visitors almost took the lead on 55 minutes, when Jay O’Shea’s right-footed strike from 20 yards flashed inches wide of the top corner.
With Walsall lacking their usual sharpness going forward, Lalkovic was brought on to inject some much-needed creativity, replacing Mantom.
And in his first involvement, the Slovakian curled a long-range free-kick around the wall but into the arms of Lee.
Lalkovic then motored forward down the left, carrying the ball half the length of the pitch, before shooting straight at the visiting custodian.
The match was meandering towards a goalless draw, with neither side looking like scoring.
Morris went closest to finding a late winner, as he rode a number of challenges before hitting a weak shot which Lee saved comfortably.
FULL-TIME: WALSALL 0-0 CHESTERFIELD – INTO EXTRA TIME…
Determined to avoid the lottery of a penalty shoot-out, Walsall flew out of the traps at the start of extra time and created a fine early chance.
Lalkovic regained possession on halfway and charged forward unopposed, broke into the box but pulled a low effort wide of the far upright.
Both sides were now pressing for a decisive goal.
An ambitious 30-yard attempt from Forde couldn’t find the target, while Sylvan Ebanks-Blake headed over from Novak’s right-wing cross.
In the second half of extra time, it was the Saddlers who were on top.
Captain Adam Chambers’ long-range, right-footed strike deflected off a defender and flew agonisingly wide with Lee scrambling across his line.
Walsall were ramping up the pressure, with Morris then striking the top of the bar with a spectacular left-footed rocket from the corner of the box.
Shortly after, Morris controlled James O’Connor’s diagonal pass and advanced into the area but his placed effort was saved by Lee.
Walsall were rampant and really should have clinched victory at the death.
Lalkovic delivered a dangerous low cross from the left but substitute James Baxendale could only side-foot wide from close range.
With the two sides unable to be separated after 120 minutes, the tie went to penalties.
Downing emerged as Walsall’s hero in the shoot-out - scoring the winning penalty after Chesterfield’s Morsy had skied his effort high over the bar.
The Saddlers netted all five spot-kicks, with Sawyers, Jason Demetriou, George Evans and Lalkovic also hitting successful penalties.
FINAL RESULT: WALSALL 0-0 CHESTERFIELD (5-3 ON PENALTIES)Team:
Etheridge, Demetriou, Taylor, O’Connor, Downing, Forde (Baxendale 105'), Chambers, Mantom (Lalkovic 68'), Evans, Sawyers, Cook (Morris 85').
Subs not used: MacGillivray, Preston, Flanagan, Morris, Kinsella.
2,953 (334 Chesterfield supporters).