Jose Mourinho pinpoints the very moment he knew Manchester United were in trouble against Derby

Manchester United manager Jose Mourinho was not a happy man after the loss to Derby in the EFL Carabao Cup on Tuesday [Courtesy]

Jose Mourinho has put his finger on the moment he knew Manchester United were in trouble against Derby on Tuesday night.

The Red Devils lost on penalties to Frank Lampard's Rams despite taking the lead in just the third minute of the third-round tie at Old Trafford.

Goals from Harry Wilson and Jack Marriott after the break saw Derby progressing to the next stage of the competition before a last-gasp Marouane Fellaini effort took the game to penalties.

Derby ran out 8-7 winners in the shoot-out but it was as the spot-kicks were being taken that Mourinho realised his Manchester United team were in serious trouble.

Derby ran out 8-7 winners in the shoot-out [Courtesy]

"We practice penalties and we see it in training and when we get past the sixth penalty I know we're in trouble with [Eric] Bailly and [Phil] Jones," explained Mourinho.

"We didn't score when we could, we could in the first half, we had situations to kill it.

"At half-time I repeated the same words as the last match. We didn't kill the game. We couldn't be dominant in the second half. I prefer to be proactive and go for it.

We practice penalties and we see it in training and when we get past the sixth penalty I know we're in trouble" - Mourinho [Courtesy]

"After the red card we are in a bit of difficulty. We reacted with pride, we tried until the last second."