Ole Gunnar Solskjaer’s side were well below their best in a scrappy fifth round tie at freezing, snow-dusted Old Trafford.
But a fine finish from Scotland midfielder McTominay ensured United advanced to the last eight for a seventh successive season.
Through to the quarter-finals! 👊🔴 #MUFC🏆 #FACup@Chevrolet
— Manchester United (@ManUtd) 1612908207000
United last won the FA Cup in 2016 and McTominay’s third goal in three games kept them in the hunt to lift the trophy for the 13th time.
After the frustration of the late Everton equaliser that dented their Premier League title challenge on Saturday, this was an essential result to lift the mood at United.
It was hardly an eye-catching performance however, with United labouring against defensive West Ham until McTominay and Bruno Fernandes were introduced as second half substitutes.
#FACup quarter-finals 🔜#MUFC @GulfOilIntl https://t.co/8JFiUU2XE3
— Manchester United (@ManUtd) 1612915144000
Amad Diallo was named on the United bench for the first time since the 18-year-old’s January move from Atalanta as Solskjaer made six changes.
Lukasz Fabianski prevented United from taking the lead in the 27th minute when he brilliantly pushed Victor Lindelof’s header onto the post.
There was a nasty clash of heads between West Ham’s Issa Diop and United’s Anthony Martial towards the end of the first half.
We did what we needed to do 💪Get the manager’s verdict after a triumphant night for United ⬇🔴 #MUFC🏆 #FACup
— Manchester United (@ManUtd) 1612914252000
Both continued after treatment but Diop did not return in the second half due to concussion.
“To clarify, Issa Diop was replaced as a concussion substitute, meaning we can now make a total of six changes, as can Manchester United, if we see fit,” West Ham said in a statement.
Fabianski saved well from Marcus Rashford before the game went into extra-time.
McTominay finally made the breakthrough in the 97th minute.
Martial’s cross was only half-cleared and Rashford’s deft touch teed up McTominay to steer a composed strike past Fabianski from just inside the area.
In Tuesday’s other fifth round tie, Burnley suffered a surprise exit as second tier Bournemouth won 2-0 at Turf Moor.
Sean Dyche’s side fell behind to Sam Surridge’s first half goal and Junior Stanislas finished them off with a late penalty.
While the loss was embarrassing, it will be forgotten if Dyche ensures Burnley retain their Premier League status.
Burnley are currently 17th in the Premier League, sitting eight points clear of the relegation zone.
It could have been an even more chastening night for Burnley, who initially included the ineligible Erik Pieters in the team before being alerted to the issue by Bournemouth’s media chief.
Dutch defender Pieters was banned after collecting bookings in the previous two rounds of the competition.
Pieters was replaced just before kick-off by Anthony Driscoll-Glennon, saving Burnley from a potential FA investigation.
“The rules have changed this year with the booking situation and the number of games in the FA Cup. It was just a clear oversight,” Dyche said.
“To be fair to Bournemouth, they flagged it and mentioned it, so credit to them for a bit of gentlemanly conduct. We jumped on it straight away and people at our club held their hands up in the right slots.”