Second-half substitutes Wes Thomas, Nathan Redmond and Ravel Morrison inspired Birmingham City to a 3-1 victory over the Rams at St Andrews.
Ben Davies’ fourth goal of the campaign had Derby in front at half-time, as the midfielder ghosted in to volley past Jack Butland from eight-yards out in the 40th minute.
However, Blues boss Lee Clarke introduced Thomas and Redmond during the interval in a double substitution, before implementing his final change, Morrison after 62 minutes.
And the trio all had a part to play in Birmingham’s turnaround, as firstly Thomas picked up Morrison’s pass before firing into the roof of the net from a tight angle, prior to Redmond unleashing an unstoppable 20-yard drive into the bottom corner.
Thomas added a third in stoppage time when he powered past the advances of Richard Keogh and Valentin Gjokaj to half-volley into the turf and past Legzdins into the corner of the net.
Prior to kick-off, Clark's side had only recorded five home League victories all season, and combined with the Rams’ recent winless run of seven matches, a tentative opening from both sides St Andrews was somewhat understandable.
Although on 13 minutes, Derby had their first sight of goal as Conor Sammon’s formidable lung busting run down the channel was thwarted by England goalkeeper Butland, who met the striker at his feet.
Three minutes later, the host’s repost saw Swindon Town loanee Paul Caddis whip a right-wing cross towards Nikola Zigic, who beat the aerial presence of the Rams’ back-line, but flicked a header wide of goal.
As the match developed, confidence began to grow within Derby’s ranks, as the lively Davies dragged a low strike wide from 20-yards, before testing Butland with a curling free-kick moments later.
Then Norwich City Academy graduate Chris Martin cut inside and sent a stinging 20-yard drive goalwards after some neat footwork; but Butland was equal to it, and produced a superb reflex stop to deny Martin his first goal in a Rams’ shirt.
However, Derby’s momentum finally proved too much for the Birmingham defence in the 40th minute, as Davies ghosted past Paul Robinson, to slam Craig Forsyth’s looping header past Butland from eight-yards out.
Striking duo Sammon and Martin both had half chances prior to the interval to double the Rams’ advantage, but the pair were denied by timely interventions from Curtis Davies and Robinson respectively.
Blues boss Clark introduced Thomas and Nathan Redmond for Peter Lovenkrands and Chris Burke at half-time in a bid to ignite the home side.
Although the duo did not have an immediate impact, the Blues certainly responded in a positive manner to whatever was said during the interval, as Callum Reilly rifled a 20-yard drive that cannoned off the crossbar after 60 minutes.
Shane Ferguson then drilled a cross to the far post only for Zigic to nod over, before Clark made his final change of the game, introducing Ravel Morrison for the unfortunate Reilly.
And it was the arrival of Morrison that sparked the Blues into life, as the former Manchester United midfielder picked out Thomas in the penalty area; the striker outmuscled Keogh and fired beyond the reach of Legzdins into the roof of the net.
Then in the 74th minute, Clark’s men completed the turnaround when substitute Redmond cut inside from the right to arrow a 20-yard drive into the bottom corner.
Keogh and Buxton both saw headers flash agonisingly past the far post in the final five minutes, but Bournemouth loanee Thomas made sure of the three points in stoppage time, when he raced clear of the Rams’ back-line to fire into the turf and past Legzdins.
Derby County: Legzdins; Gjokaj, Keogh, Buxton, Roberts; Davies (Jacobs 80), Coutts, Hendrick, Forsyth; Martin, Sammon
Subs not used: Fielding, Hoganson, O’Brien, Freeman, Bennett, Doyle
Birmingham City: Butland; Caddis, Davies, Robinson, Ferguson; Burke (Redmond 46), Reilly (Morrison 62), Spector, Elliott; Lovenkrands (Thomas 46), Zigic
Subs not used: Doyle, Caldwell, Mullins, Fahey
Attendance: 15,850 (1,317 visiting supporters)