United were also eliminated early in the EFL Cup, losing on penalties to Championship side Derby County in the third round.

The club reached the quarter-final stage of both the FA Cup and the UEFA Champions League, but were eliminated by Wolverhampton Wanderers and Barcelona respectively.

[3] The following day, former United striker Ole Gunnar Solskjær was appointed as caretaker manager until the end of the season, assisted by former coach Mike Phelan, who had left the club in 2013 following the retirement of Sir Alex Ferguson.

[8] Alexis Sánchez's arrival in the United States was delayed as he was not issued with a visa due to the 16-month suspended jail sentence he accepted in February for tax fraud during his time in Spain.

[64] The draw for the third round of the EFL Cup was made on 30 August 2018, with Manchester United drawn at home to Derby County.

[79] After finishing second in their group and progressing to the round of 16, United were drawn against French champions Paris Saint-Germain in the first competitive meeting between the two sides.

[79] In the first leg at Old Trafford, goals from Presnel Kimpembe and Kylian Mbappé gave PSG a 2–0 lead to take back to the Parc des Princes.

Former Manchester United midfielder Ángel Di María had the ball in the back of the net early in the second half, only for the goal to be ruled out for offside, and Bernat hit the post late on after Mbappé had rounded David de Gea.

[81] Solskjær gave 17-year-old forward Mason Greenwood and 19-year-old winger Tahith Chong their European debuts, the former also playing his first senior game.

The second leg was played at Camp Nou on 16 April, with two goals from Lionel Messi and another from former Liverpool forward Philippe Coutinho giving the Spanish side a 3–0 win on the night, 4–0 on aggregate.