Title-chasing Rams grabbed an 88th-minute winner when Adam Bolder's free-kick was nodded back into the danger area by Gary Twigg for Marcus Tudgay to loop a header past the despairing dive of Lars Hirschfeld.
It was a little hard on the lads after they turned up the heat in the second half, eventually levelled through Steven Ferguson, pictured, and arguably deserved at least a point. Instead, Billy McEwen's fired-up visitors completed the double and stayed in the hunt for the FA Premier League championship.
Derby just about edged a scrappy first half and took the lead after 11 minutes when Steve Elliott rose well to head home Bolder's corner.
Chris Armstrong caused panic a couple of times in the visiting defence but John Jackson came closest for us in the first half with a scorching 20-yarder that Patrick Foletti did well to tip aside. Hirschfeld was also tested as Elliott caused problems again before the break.
Armstrong underlined our second half intentions within a minute of the restart. His break and lovely pass with the outside of his foot released Ferguson into the box but his goalbound effort clipped the lunging foot of Elliott and slipped just wide.
Play stayed mainly in midfield until our best spell in the last quarter of the game.
Ironically enough, Matt O'Halloran almost doubled Derby's lead in that spell, his sweet volley hitting the inside of the post onto Ron Henry's knee and bouncing over, but we soon hit back.
John Piercy produced the pass of the game to release Mauricio Taricco down the left flank, he found Jackson who set up Ferguson's stinging shot that Foletti did well to palm out.
We grabbed the equaliser after 83 minutes and it was all about Jackson. He picked the ball up 30 yards out and wriggled past three defenders into the area, Foletti parried his effort but the lively Ferguson was there to stab home the rebound.
Unfortunately parity lasted only five minutes. Bolder's free-kick to the far post was headed back across goal by Twigg and Tudgay squeezed between defenders to loop his header home from 10 yards.
We still managed one last effort as Foletti superbly tipped aside Jackson's low drive but time ran out as we pushed for a second goal.
Spurs Res: Hirschfeld, Bowditch, Taricco, Henry, O'Donoghue, Clemence, Snee, Piercy (Marney, 74), Armstrong (Barnard, 66), Jackson, Ferguson. Unused subs: Burch, Hughes, Galbraith.
Derby Reserves: Foletti, Mawene, Elliot, Hunt, Evatt, Mcardle, Bolder, O'Halloran, Tudgay, Mills, Twigg. Unused subs: Weckstrom, Molloy, McKeown.
Derby County's late, late show left Colin Calderwood's young reserve side wondering what could have been at Stevenage Borough last night.