Mark Hudson powered Chesterfield into thirrd place in League Two and pushed Paul Merson's Saddlers deeper into the relegation mire.
Hudson's 22nd minute strike was scant reward for a superb first-half display from Chesterfield.
Their passing football was some of the best seen at Saltergate for years but in the end they were left hanging on as Merson's men staged a second half revival.
The skill of Jamal Campbell-Ryce, on loan from Charlton, coupled with the power and an eye for goal of Tcham N'Toya-Zoa proved more than a handful for Walsall's experienced defenders. Neil Emblen, Mark Kinsella and Jorge Leitao were all booked in a 15 minute purple patch as they tried to stem the on-rushing tide of Chesterfield attacks.
For all the home side's dominance, they went in just a goal ahead at half time, and a very different 45 minutes was to follow.
Merson took off Emblen at the break and substitute Ian Roper took over in defence and showed how to curb the threat of Tcham N'Toya-Zoa, with a gritty display.
Mark De Bolla set up Campbell-Ryce with a delightful back heel and the wingers shot flew just wide. Chesterfield saw little else of the Walsall goal.
Prompted by Merson's passing and the running of substitute Daryl Taylo, Walsall got the upper hand and laid siege to the Chesterfield goal. Merson punched the turf in frustration after heading wide from close range and then Matt Fryatt was guilty of a similar error from a corner.
Leitao ran fully 50 yards through the home defence but then got in a tangle and allowed Carl Muggleton to smother his shot.
Leitao was also guilty of heading wide a Merson cross and Julian Bennett blazed a chance over as Chesterfield hung on to maintain their run up the table.