Manchester United crashed out of the Carabao Cup with a defeat on penalties to Championship side Derby County on Tuesday after the third-round tie ended 2-2 in normal time at Old Trafford.
With no extra time in this season's competition, the contest went straight to spot kicks and Frank Lampard's Derby won 8-7 with Phil Jones's effort saved by visiting keeper Scott Carson.
United manager Jose Mourinho said he felt his team were in difficulty once the shootout got down to his defenders.
"I knew that we were going to be in trouble, with Jones with Eric [Bailly] I knew that we were going to be in trouble then," he said.
For former England midfielder Lampard, who played under Mourinho at Chelsea, it was just reward for playing a full-strength side and approaching the game in positive fashion.
"I wanted to bring a team who could really compete. I am so proud of them," said Lampard, in his first season as a manager.
"I am trying to build a group to be successful and nights like this are incredible. To go against world-class players and play that way, it's right up there," he added.
Derby had been moments away from winning 2-1 in normal time after United keeper Sergio Romero was sent off in the 67th minute but Marouane Fellaini got a stoppage-time equaliser.
United had taken the lead against Derby in the third minute with a well-placed shot from Juan Mata after Anthony Martial had burst down the left flank.
However, the visitors drew level in spectacular fashion after 59 minutes with a brilliant bending free kick from Harry Wilson, the young Welsh winger on loan from Liverpool.
Eight minutes later, Romero was dismissed for handling outside the box and Derby grabbed what they thought was the winner when United's substitute keeper Lee Grant parried a shot from Mason Mount and Jack Marriott nodded in the loose ball.
But in the fifth minute of added time, substitute Fellaini headed in a Diogo Dalot cross to force the shootout.