The Ivory Coast international scored a 90th-minute winner to complete a late turnaround in Sunday's 2-1 win over Manchester City at the Etihad Stadium.
Diallo calmly lifted the ball over Ederson after latching onto Lisandro Martinez's long pass, before he kept his composure to squeeze the ball in from a tight angle.
Not only did he clinch three precious points, but Diallo also continued his fine form under Man United head coach Ruben Amorim.
Diallo has now registered one goal and four assists in five Premier League matches since Amorim replaced Erik ten Hag in November.
Man United step up Diallo contract talks
While Diallo may be developing into a key player, there is some uncertainty surrounding his long-term future with the Red Devils.
Diallo's current contract is set to expire at the end of the season, although Man United do have the option to trigger a one-year extension.
Earlier this month, Amorim promised to "find a solution" when asked about the Ivorian's contract situation at Old Trafford.
According to Football Insider, Man United are now stepping up their efforts to come to a swift agreement with Diallo over a new contract.
The report claims that an agreement between the two parties is 'not far off' with remaining discussions 'expected to be a formality.
When will Diallo's contract be agreed?
While Man United are making significant progress, they are yet to reach a final agreement with Diallo over a new contract.
However, there is a belief that Man United could agree a new deal on improved terms by the end of the calendar year.
The 20-time English champions are seemingly keen to offer Diallo a contract which reflects his recent form and his importance to the squad.
If Man United are unable to finalise a new deal by the end of the month, Diallo would be able to negotiate pre-contract agreements with overseas clubs from January.
However, there is no sign that the attacker wants to leave Old Trafford, especially as he has demonstrated he is a suitable fit for Amorim's 3-4-3 system.
Written by
Ben Sully