The teenage wing-back is currently trialling with United and has impressed during this week's Milk Cup campaign in Northern Ireland.
Borg caught the eye of United scouts after shining for West Ham last season and is weighing up his options ahead of turning pro.
The youngster's father, Dean, told tribalfootball.com: "West Ham are indeed still in the picture as his 'parent' club but there are many things to consider for any young lad and it's not one we intend to rush Oscar on."
Borg is enjoying his time with United and Dean added: "It gives MUFC a good opportunity to see what he's all about over a decent period of time and for him the experience of all that is MUFC.... which needless to say is impressive."
United could extend Borg's trials beyond the current Milk Cup campaign. The left-sided wing-back has played the full 90 of United's two games so far.
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