At a Glance
The Red Devils' disappointing run of form persisted at Leeds' fortress, but manager the Portuguese tactician had his Brazilian forward to thank for the team avoiding even more damage against their old rivals.
Dominic Calvert-Lewin headed a first-half effort against the woodwork for the in-form hosts before Brenden Aaronson finished superbly with a driven, 62nd-minute shot.
With the goal, Amorim was under intense scrutiny after his side had been held by struggling Wolves at Old Trafford earlier in the week.
Nevertheless, against opponents who had two days less to recover, Cunha levelled three minutes after the opener when he ran on to a through ball from substitute Joshua Zirkzee and guided a shot underneath rushing home goalkeeper Lucas Perri.
It was only the Brazilian's fourth goal since his high-profile summer move and came at a time when the manager is without several key attacking players due to a mix of injury and national team commitments.
Not that you would expect the hosts to sympathise with that given their own lack of preparation time.
The Swiss attacker forced a diving save out of visiting goalkeeper Senne Lammens with a spectacular overhead kick, and visiting heads were in hands when the Slovenian striker, who is struggling to make an impact, turned Zirkzee's cut-back wide from six yards out.
The goalscorer, who had a goal ruled out for offside much earlier in the contest, also fired against a post in the dying moments.
The point prolongs the home side's unbeaten run to seven matches, their longest such streak since over two decades ago, and takes them eight points clear of the relegation zone.
For the visitors though, it was yet another opportunity to move into fourth spot, albeit only for a short time, squandered.
With the AFCON reaching its knockout phase, Amorim could be forgiven for hoping the involved countries make a swift exit.
Existing injuries to skipper Bruno Fernandes and England international Mason Mount only exacerbated the impact the unavailability of other attackers is having on the team's squad.
It's not that the missing pair are the answer to all of the club's problems. After all, they were part of the side that experienced disappointing results earlier in the campaign.
But without them, the boss has few alternatives in attack.
He evidently does not have full faith in teenager Shea Lacey or the seasoned Joshua Zirkzee, even though the Dutch forward provided the assist for the equaliser almost instantly after his introduction as a substitute.
That leaves the Brazilian, who has now scored a small tally in recent outings, and others operating out of their natural positions, alongside Benjamin Sesko.
On this showing, the expensive frontman looks similar to previous struggling signings, lacking in belief and assurance in front of goal.
His 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 bit drab affair.
True, there were moments of typical atmosphere, but the intimidating edge was not as evident as in previous encounters.
Leeds' fans were more preoccupied about their side's struggle to get worthwhile possession in dangerous areas for any prolonged period.
The Calvert-Lewin header that clipped the post was an isolated moment of quality in a tight first half.
It still felt as though the hosts were struggling when a defensive error opened the door for the opener.
Ever so briefly, The home delirious fans thought they were about to secure a rare win against their old foes.
However, there is a much bigger picture for the manager and Leeds to deal with.
When they endured a difficult run of form earlier in the season, many speculated about the manager's future.
Instead, he is now masterminding significant improvement.
The task is not done yet but gradually, the team are getting closer to achieving their top-flight status.
Leeds have a Premier League trip to St James' Park in midweek, followed by the start of their FA Cup campaign next weekend. Manchester United face a Premier League trip to Turf Moor before also entering their FA Cup journey with a Old Trafford tie.
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