Frank Lampard has enjoyed some famous victories alongside Jose Mourinho over the years, but few can have tasted as sweet as this on a night of drama at Old Trafford.
As goalkeeper Scott Carson lunged to his left to smother Phil Jones' weak penalty, Lampard pumped his arms in jubilation on the touchline. This was the finest moment of his fledgling managerial career and a well deserved one at that.
Yards away, Mourinho hung his head and contemplated the latest setback of an increasingly dismal season.
Eight points adrift in the Premier League, Manchester United are now out of the Carabao Cup at the first hurdle as well.
Up in the stands, Paul Pogba tried to hide under a white hoodie as the drama unfolded. Rested for the night amid renewed uncertainty over his future at United, would Pogba have made a difference?
Possibly but Mourinho had enough big guns on the pitch to get the job done against Championship opposition, and once again they came up short.
United thought they had salvaged this third round tie when Marouane Fellaini headed home deep into injury-time after Derby took the lead against a team reduced to 10-men by Sergio Romero's sending-off.
But with extra-time no longer required in this competition, and the two teams level in the shootout after scoring each of their first seven attempts, Andy Keogh converted for Derby and Jones failed for United.
It was the fifth time in a row that United have lost a penalty shootout.
Lampard led his players over to the corner of the pitch where their fans were celebrating and milked the moment. They had deserved it.
-Dailymail