Ian Taylor's controversial first-half penalty earned Derby a draw at Bramall Lane, which was enough to move the Rams out of the relegation zone and severely dent Sheffield United's automatic promotion hopes.
The Blades missed out on a chance to put pressure on joint-leaders Norwich and West Brom, and are now seven points adrift of the pacesetters having played a match more.
For Derby, meanwhile, the point moves them above Burnley and level with Rotherham. However, their record of 15 games without a win on their travels goes a long way to explaining their precarious predicament.
It had all looked so much more positive for the Blades when they took the lead after 21 minutes.
Derby right-back Rob Edwards failed to deal with Michael Tonge's cross under pressure from Peter Ndlovu, and Andy Gray scuffed the ball past Lee Grant.
However, the euphoria lasted just four minutes.
Leon Osman, impressing during his loan spell from Everton, chased down a long clearance.
Nick Montgomery appeared to get in a good challenge on the edge of the box to put the ball out for a corner, but referee Lee Mason pointed to the spot leaving Bramall Lane - and in particular Blades boss Neil Warnock - in uproar.
Taylor despatched the resulting penalty, sending Paddy Kenny the wrong way.
Blades fans had been cautious about their team's chances of automatic promotion, given the gap between them and the top two, but knew a victory would certainly up the pressure.
The Rams, meanwhile, had travelled up the M1 with just one defeat in their last four games, but they were deprived of one of the main reasons for that record - the goals of Paul Peschisolido who has scored four in his last three
matches but was ineligible following his switch from the Blades.
The home side certainly dominated the opening stages, but struggled to carve out clear chances apart from their goal.
Phil Jagielka did have a header cleared off the line by Adam Bolder following a Tonge corner, but six first-half bookings told a very different story.
In the end, though, the Blades could not find a way past a resolute Derby backline again after the break.
And Warnock himself left the field less than impressed with the performance of the match officials, and appeared not afraid to let his feelings be known to them as they walked off.
Teams
Sheff Utd Kenny, Phil Jagielka, Morgan, Page, Kozluk,
Ndlovu (Boussatta 67), Montgomery, McCall (Forte 67), Tonge,
Gray, Lester, Boussatta (Allison 81).
Subs Not Used: Shaw, Francis.
Booked: Page, McCall, Ndlovu, Morgan.
Goals: Gray 21.
Derby Grant, Edwards, Johnson (Walton 8), Mawene, Bolder,
Boertien, Taylor, Huddlestone, Osman, Tudgay (Whelan 90),
Manel (Costa 78).
Subs Not Used: Oakes, Labarthe Tome.
Booked: Osman, Manel, Bolder.
Goals: Taylor 25 pen.
Att: 21,351
Ref: L Mason (Lancashire).