The Rams appeared to be heading for a 2-1 victory at Fratton as the relegation clash entered six minutes of time added-on.
However, Rob Atkinson, who had earlier scored his maiden Pompey goal before putting through into his own net, rode to the rescue by heading home Nicolas Schmid’s long goal kick.
Days earlier the Blues lost in agonising circumstances at Coventry, now they had earned a precious point – and here are Neil Allen’s player ratings...
5. Jordan Williams - 5
Came in at left-back in Swanson’s absence and, crucially, lost Ward in the build-up for Derby’s equaliser on the stroke of half-time. Had a great second-half chance to tee up Segecic, but produced a poor pass. Photo: Dan Istitene
6. Andre Dozzell - 7
Found himself with another central midfield partner, with Kosznovszky alongside him this time. Booked late in the first half after pulling back Agyemang to prevent a counter-attack. Spent much of his time chasing and harrying rather than dictating play. Photo: Graham Hunt
7. Mark Kosznovszky - 6
(Replaced by Marlon Pack on 66 mins) Chosen ahead of Pack and Swift in the centre of midfield, the Hungarian was again neat and tidy, keeping things simple. Awful misplaced pass on 31 minutes almost gifted Derby a goal, but Schmid rescued him. Photo: Simon Roe
8. Conor Chaplin - 5
(Replaced by Adrian Segecic on 66 mins) Always wants the ball, always encouraging, team-mates, always on the move, but it just didn’t happen for him. Too careless in possession at times and a real off-day. Photo: Stephen Flynn