Lee Bradbury's controversial late penalty gave Walsall a crucial victory at relegation rivals Derby.
Derby were left furious and deep in trouble after defender Michael Johnson was sent off for a foul on Bradbury.
Manuel Manel came close for Derby and Leon Osman also tested goalkeeper James Walker as the home side pressed.
But Walsall snatched the late win and almost added a second when substitute Jermaine McSporran rattled the woodwork in the dying seconds.
Both sides carved out plenty of chances between them in the opening 45 minutes, but as the game wore on it was the home side who looked the more
The visitors created the first clear opening after four minutes when Zigor Aranalde's cross found Jorge Leitao, but he sent his close-range header wide.
Darren Bazeley then saw his shot saved by Derby goalkeeper Lee Grant as Walsall continued to press. Paul Merson tried his luck from distance, but was
Close range volley
Walsall keeper Walker had to be on his toes to deal with Paul Peschisolido's sharply-struck shot after 10 minutes.
But, with the game opening up, Walker's opposite number Grant parried an effort from Leitao shortly afterwards.
Derby began to gain the upper hand as the half wore on with Manuel having his fiercely-struck effort blocked by Ian Roper on the half hour.
Derby were forced to replace the injured Paul Boertein with Rob Edwards, but they started the second half strongly.
And they almost gained the breakthrough 10 minutes after the interval, only for Walker to keep out Osman's close-range volley.
Walker was again the hero for Walsall with an excellent save from Tom Huddlestone's piledriver after 70 minutes.
With the home side continuing to push for a winner Ian Taylor saw his mis-hit effort drift wide nine minutes from time.
Derby: Grant, Kenna, Mawene, Johnson, Boertien, Costa, Taylor,
Huddlestone, Osman, Peschisolido, Manel. Subs: Oakes, Edwards,
Bolder, Reich, Junior.
Walsall: Walker, Bazeley, Emblen, Roper, Aranalde, Osborn,
Burley, Merson, Andrews, Leitao, Bradbury. Subs: Petterson,
Carbon, Wright, Kris Taylor, McSporran.
Referee: M Jones (Cheshire).