Key Moments
The Red Devils' disappointing run of form persisted at Leeds' fortress, but manager the Portuguese tactician had Matheus Cunha to thank for his side not suffering even more damage against their old rivals.
The Everton loanee headed a first-period attempt against the post for the confident hosts before Brenden Aaronson finished superbly with a driven, 62nd-minute effort.
At that stage, Amorim was under intense scrutiny after his side had failed to beat bottom-of-the-table Wolves at home earlier in the week.
Nevertheless, against opponents who had two days less to prepare, Cunha restored parity three minutes later when he latched onto a through ball from substitute the Dutchman and guided a shot underneath advancing home goalkeeper Lucas Perri.
It was only the South American's fourth goal since his high-profile summer move and came at a time when Amorim is without four key attacking players due to a mix of injury and international duty.
Not that the hosts to sympathise with that given their own tight schedule.
Noah Okafor forced a diving save out of visiting goalkeeper Senne Lammens with a spectacular overhead kick, and United heads were in hands when the Slovenian striker, who is finding it hard to make an impact, turned his teammate's cut-back wide from close range.
The goalscorer, who had a goal ruled out for offside much earlier in the match, also fired against a post late on.
The point prolongs Leeds' unbeaten run to seven games, their best such streak since over two decades ago, and takes them eight points clear of the relegation zone.
For the Manchester United though, it was yet another chance to move into fourth spot, albeit only for a short time, wasted.
With the AFCON reaching its knockout phase, Amorim could be forgiven for hoping the participating nations make a pretty quick exit.
Current injuries to captain Bruno Fernandes and England international Mason Mount only heightened the impact the absence of other attackers is having on Amorim's squad.
It's not that the absent players are the solution to all of the club's problems. After all, they were part of the side that experienced poor results earlier in the season.
But without them, the boss has limited alternatives in attack.
He clearly does not trust teenager Shea Lacey or the seasoned Zirkzee, even though the Dutch forward provided the through ball for the equaliser almost instantly after his introduction as a substitute.
That leaves the Brazilian, who has now scored a small tally in five games, and others playing out of their preferred positions, alongside Sesko.
On this showing, the big-money frontman looks similar to previous struggling signings, lacking in belief and conviction in front of goal.
Sesko's failure to turn home Zirkzee's cross means it is now a long run without a goal for the young striker.
After memorable victories in their last few home games, the arrival of their fiercest rivals to home was a comparatively subdued affair.
True, there were instances of expected atmosphere, but the hostile edge was not as pronounced as in other encounters.
Leeds' fans were more concerned about their side's struggle to get worthwhile possession in dangerous areas for any length of time.
The Calvert-Lewin header that struck the post was an isolated moment of threat in a congested first half.
It still felt as though Leeds were finding it tough when a mistake opened the door for the opener.
Ever so briefly, Leeds' delirious fans thought they were about to secure a coveted win against their old foes.
However, there is a much bigger picture for the manager and Leeds to deal with.
When they suffered a difficult run of form earlier in the campaign, many thought about the manager's position.
Instead, he is now overseeing clear improvement.
The task is not done yet but gradually, the team are getting closer to securing their top-flight status.
Leeds have a top-flight trip to Newcastle in midweek, followed by the start of their FA Cup campaign next weekend. Manchester United face a league trip to Burnley before also entering their FA Cup journey with a Old Trafford tie.
A passionate educator and researcher with over a decade of experience in molecular biology and science communication.
