The forward was one-on-one with the goalkeeper in the first half, but lofted his effort over the bar. It prompted this reaction from the United boss, who was clearly unhappy with his player's profligacy:
After receiving some criticism from pundits for the way he responded to the miss, Mourinho defended his actions, per Mark Critchley of The Independent:
"We don't score enough goals, but it is not about Marcus. It is about us as a team, it is very difficult for us to score goals but Marcus makes the movement, makes the runs, works hard when the team has the ball and doesn't have the ball.
"I can never, never, blame a player because of missing chances. Can I have on the touchline—where not a lot of the ones that comment on football, they were there; not many of them were there—can myself or another manager have a reaction of frustration?"
Mourinho also invited the pundits to try their hand at management, but said "maybe it is better to have lots of holidays in Barbados and go to the television screen and touch the electronic dummies."
Former England international Gary Lineker, who was the anchor on BT Sport as it broadcast the game, provided more context to his remarks on Twitter:
Samuel Luckhurst of the Manchester Evening News said he thinks the United No. 10 needs to become more clinical when presented with those types of opportunities:
In the end, the Red Devils and Mourinho weren't left to rue Rashford's miss, as a last-gasp goal from Marouane Fellaini was enough to give United a 1-0 win and earn their spot in the knockout stages of the competition.
Mourinho reacted with frustration following the goal, taking a crate of energy drinks on the sidelines and slamming them into the ground.
While the team have made it into the last 16 with a game to spare, a look beyond the result itself shows another tepid performance from Mourinho's side against modest opponents. Bleacher Report's Rob Blanchette thinks the late goal shouldn't gloss over the poor display:
Rob Blanchette @_Rob_B
The type of performance I thoroughly expected, and content I didn't bother going to Old Trafford tonight. An utterly embarrassing display again. Young Boys were missing their 3 best players, but Mourinho dodges another bullet with his tiresome long ball style. Bravo, Jose. #MUFC
Mourinho has developed a reputation for not giving young players opportunities throughout his career. Last week the Red Devils manager also said the likes of Rashford, Luke Shaw, Anthony Martial and Jesse Lingard are "lacking" in certain areas, per Jamie Jackson of the Guardian.
This season Rashford has scored two goals in the Premier League, the most recent being a last-minute winner over Bournemouth. While Mourinho's reaction will unsurprisingly rile some, the forward also needs to become ruthless in front of goal if he's to lead the line at United for years to come.