Al Bangura's dramatic injury-time strike earned Watford a point but did little to boost their chances of catching Sheffield United in the race for the second automatic promotion spot.
The teenage substitute fired in an excellent right-footed 20-yard half volley in the fourth of six minutes of stoppage time to net his first senior goal, soon after Giles Barnes had done likewise to seemingly put Derby County on course for a shock away victory.
But the Rams ultimately paid the price for their delaying tactics, particularly in the second half, which had largely succeeded in frustrating the Golden Boys in their attempts to gain the victory that would have moved them within five points of second place in the Championship.
Watford started in a manner which suggested they could win a ninth league game in ten and Ashley Young should have given them an early lead.
The winger was denied by alert Rams goalie, Lee Camp after being put through on goal but then glanced an even better chance wide of the target after being picked out by Marlon King's follow up cross.
Instead it was visitors who drew first blood in the 19th minute when the Hornets offside trap failed and on-loan striker Kevin Lisbie broke clear.
Although Jordan Stewart got back to win a challenge, the defender then appeared to slip and Lisbie managed to squeeze a shot beyond Ben Foster and the ball entered the net via the far post and Clarke Carlisle's desperate attempts to clear.
Watford then struggled against the Midlanders' five man midfield, but managed to equalise in real style with the Championship's leading scorer King netting his 18th goal of the season.
The former Nottingham Forest frontman collected a long Foster free-kick on the edge of the Derby County area and held off Darren Moore before creating space to slam a low 20-yard right foot drive past a diving Camp.
With parity restored the home team attacked with real purpose and as half time approached Hameur Bouazza should have put the hosts in front but blazed badly over from just six yards out.
Watford bossed most of the play after the break as well, but increasingly became frustrated by Derby's time wasting tactics which earned Camp a booking and Rams manager, Terry Westley later described as "bonkers".
Attack minded Watford continued to push forward in numbers and King soon hit a post with Camp beaten, but it looked like Derby County would snatch all three points when, four minutes from time, a long throw was flicked on by Adam Bolder to Barnes who confidently beat Foster from 18 yards with a low left foot drive.
However, the Golden Boys have shown on several occasions this season that they do not know when they are beaten and this characteristic came to the fore again in injury time when the diminutive Bangura equalised to send the Vic wild with delight.
So a point apiece and the Golden Boys ultimately failed to take advantage of Sheffield United's slip up against Crewe Alexandra the previous night, and drop a place in the Championship table, a consequence of Leeds United's fine 2-1 victory at play-off chasing Crystal Palace.
However, the promised land of the Premiership still remains a realistic target, a goal not lost on Watford manager Aidy Boothroyd, who remained in typically confident mood when interviewed afterwards,
"If we win our next nine matches between now and the end of the season I think we'll do it.
I believe we'll get an automatic promotion spot.
There are a lot more twists and turns to be taken between now and the end of the season and all I'm doing now is focusing on the next game."
Golden Boys man of the match: Marlon King