Key Moments
The Red Devils' disappointing recent struggles continued at Elland Road, but head coach the Portuguese tactician had his Brazilian forward to thank for the team not suffering even more disappointment against their old rivals.
The Everton loanee directed a first-period attempt against the woodwork for the confident hosts before the American midfielder applied a cool finish with a low, 62nd-minute shot.
With the goal, Amorim was in the firing line after his side had been held by bottom-of-the-table Wolverhampton Wanderers at home earlier in the week.
Nevertheless, against opponents who had less time to prepare, Cunha levelled three minutes later when he latched onto a through ball from introduced Joshua Zirkzee and slid a finish underneath advancing Leeds goalkeeper Lucas Perri.
It was only the Brazilian's fourth goal since his big-money summer move and came at a time when the manager is without four key attacking players due to a mix of fitness issues and international duty.
Not that you would expect the hosts to sympathise with that given their own tight schedule.
Noah Okafor forced a diving save out of Manchester United goalkeeper Senne Lammens with a spectacular overhead kick, and visiting heads were in hands when Benjamin Sesko, who is struggling to make an impression, turned his teammate's cut-back wide from six yards out.
The goalscorer, who had a goal disallowed for offside much earlier in the match, also fired against a post late on.
The draw extends Leeds' unbeaten run to seven matches, their best such streak since over two decades ago, and takes them eight points clear of the drop zone.
For the Manchester United though, it was yet another opportunity to move into the Champions League places, albeit only for a matter of hours, squandered.
With the AFCON reaching its knockout phase, the United coach could be understood for hoping the involved countries make a swift exit.
Existing injuries to captain Bruno Fernandes and Three Lions star Mason Mount only exacerbated the impact the absence of other attackers is having on the team's squad.
It's not that the absent players are the solution to all of United's problems. After all, they were part of the side that suffered poor results earlier in the campaign.
But without them, the boss has limited alternatives in attack.
He clearly does not trust youngster Shea Lacey or the seasoned Zirkzee, even though the Netherlands forward delivered the assist for the equaliser almost instantly after his arrival as a substitute.
That leaves Cunha, who has now scored three goals in recent outings, and others playing out of their preferred positions, alongside Sesko.
On this evidence, the big-money frontman looks similar to previous underwhelming signings, lacking in belief and conviction in front of goal.
Sesko's failure to turn home the cross means it is now a long run without a goal for the new signing.
After memorable victories in their previous home games, the arrival of their fiercest rivals to home was a comparatively subdued affair.
True, there were instances of expected fervor, but the intimidating edge was not as evident as in previous fixtures.
Leeds' fans were more preoccupied about their side's inability to get sustained possession in dangerous areas for any prolonged period.
The Calvert-Lewin header that clipped the post was an rare 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 Aaronson.
For a short moment, Leeds' ecstatic fans thought they were about to secure a coveted win against Manchester United.
Nevertheless, there is a much bigger picture for the manager and the club to deal with.
When they endured a poor run of form earlier in the season, many thought about the manager's future.
Instead, he is now overseeing significant improvement.
The task is not completed yet but gradually, the team are getting nearer to securing their survival.
The Yorkshire club have a Premier League 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 beginning their cup journey with a Old Trafford tie.
A passionate golfer and journalist with over a decade of experience covering PGA tours and equipment innovations.