Derby recovered from a two-goal deficit to edge past Southampton 5-3 on penalties in a thrilling FA Cup third-round replay at St Mary's.
Two goals in two minutes from Stuart Armstrong and Nathan Redmond had put the hosts on course for victory, after the visitors had earlier had a Craig Bryson goal disallowed by VAR.
But Harry Wilson's free-kick sparked a revival before Martyn Waghorn headed a late equaliser for Frank Lampard's side.
Redmond missed in the shootout for Southampton, allowing Rams captain Richard Keogh to strike the winning penalty.
Derby travel to League One Accrington in the fourth round on Saturday, 26 January (12:30 GMT).
Inseparable after 210 minutes
For the second successive meeting Derby displayed resilience to recover after falling two goals behind to Southampton, leaving the sides inseparable after 210 minutes of football.
In a game full of incident, it seemed the visitors had drawn first blood when Bryson produced a composed left-footed finish past Saint goalkeeper Angus Gunn in the first period.
But after a wait of two minutes, VAR judged forward Waghorn to be marginally offside before he played in the midfielder.
The introduction of Redmond helped Saints up the tempo after the break and they looked to have put the tie to bed with two goals in two minutes.
First Armstrong nodded in from close range to conclude a fine move involving Mohamed Elyounoussi and Shane Long. Jack Stephens then released Redmond who delivered a deft chip over Rams goalkeeper Kelle Roos.
Derby arrived on the south coast having lost eight of their past nine FA Cup games at Premier League opponents, but that statistic was clearly not on the players' minds as they surged forward to force a free-kick that Wilson curled home beyond Gunn - but only after more anxious moments following a VAR review.
And the battling visitors pulled level when Waghorn found the top corner with a well-placed header, forcing a goalless period of extra time before the successful shootout against last season's semi-finalists.
Derby's players showed great composure to convert all five of their penalties, with Southampton's only failure from 12 yards coming from the otherwise impressive Redmond, who sent an ugly effort wide of the mark.
-- Courtesy of BBC Sport