Jordy Hiwula scored an 88th-minute winner as Walsall moved to within three points of the automatic promotion places with victory over Southend.
The Saddlers dominated throughout but found Shrimpers keeper Dan Bentley in phenomenal form as he saved from Sam Mantom, Hiwula and Kieron Morris.
Anthony Forde also struck a post for the dominant hosts, who finally broke the deadlock when Morris’ corner was headed in via the bar by Hiwula.
Jon Whitney’s side remain third in League One but are now just three points behind second-placed Burton with a game in hand.
The Saddlers have now won five of their seven matches since Whitney took charge.
Walsall were unchanged from the team that beat Gillingham 2-1 on Tuesday evening.
The hosts started purposefully and almost took the lead inside the first minute, when Sawyers’ right-wing cross floated over Bentley and dropped just wide.
Phil Brown’s Southend then threatened through Will Atkinson who glanced a header harmlessly wide from Ryan Leonard’s centre.
Home keeper Neil Etheridge was employed for the first time on 13 minutes, as he comfortably held Tryone Barnett’s firm header from David Worrall’s delivery.
Rico Henry then went close when he carried the ball forward and unleashed a spectacular long-range drive which whistled just wide.
At the other end, Jack Payne cut inside from the right before drilling wide of Etheridge’s near post.
After a fairly quiet and evenly-contested opening 25 minutes, Walsall began to dominate.
Sam Mantom’s well-struck right-footed effort was pushed away by Bentley, before Jason Demetriou’s ambitious, swerving 35-yarder flew narrowly wide.
Shortly after, a Forde corner ran through for Sawyers to fire a low shot goalwards but Gary Deegan was perfectly positioned to clear off the line.
After Sawyers curled wide from the edge of the area, Walsall were then denied an opening goal by an incredible triple save from Bentley.
Lalkovic’s effort from a tight angle was kept out by the visiting stopper, who then parried Sawyers’ 20-yard strike before blocking Hiwula’s follow-up.
The ball came back out to the on-loan striker but with the goal at his mercy, he sliced disappointingly wide when he should have scored.
HALF-TIME: WALSALL 0-0 SOUTHEND
Walsall made a lightning quick start to the second period and continued to create chances.
On 47 minutes, Sawyers played in Hiwula, who was denied by the legs of Bentley, with Forde then seeing a low shot rattle the post.
Moments later, Bentley produced another fine stop to turn away Mantom’s near-post drive.
Walsall continued to push forward, with Lalkovic shooting straight at Bentley, who then held Forde’s shot on the turn.
Southend’s first attempt of the second half came on 72 minutes, Deegan with a dipping long-range strike which was superbly tipped over by Etheridge.
Substitute Kevan Hurst went close to making the breakthrough with a low strike which the impressive Matthew Pennington blocked from virtually on the line.
With time running out, Walsall threw caution to the wind in search of a winner, with substitute Morris twice going close.
First, Forde’s left-wing corner ran through to the far post for Morris to fire into the side-netting.
And then, Morris’ superb left-footed strike appeared to be heading for the top corner but Bentley produced a magnificent one-handed save to turn the ball away.
It looked as though Walsall would have to settle for a draw but with two minutes remaining, they finally grabbed that elusive goal.
Hiwula met Morris’ corner with a powerful close-range header which crashed against the underside of the bar and bounced just over the line.
It sparked wild scenes and moments later it could have been 2-0 but Bentley got down smartly to deny Morris.
Southend pushed for a late leveller, with captain Adam Barrett sending a dipping effort goalwards which Etheridge tipped over as Walsall deservedly held on.
FULL-TIME: WALSALL 1-0 SOUTHEND
Team: Etheridge, Demetriou, Downing, Pennington, Henry, Chambers, Mantom (Cook 80’), Forde, Lalkovic (Morris 74’), Sawyers, Hiwula.
Subs not used: MacGillivray, Taylor, O’Connor, Preston, Kinsella.
Attendance: 5372 (428 Southend supporters).