The 19-year-old was signed for 3million euros from Colombian club Envigado in the summer but has impressed with the maturity of his performances in Serie A - so much so that Paris St Germain have also been monitoring him.
Pescara cashed in by selling talented midfielder Marco Veratti to the mega-rich French club for £12million in the summer and are sensing that a major bidding war could be about to break out for their newest discovery.
Pescara sporting director Daniele Delli Carri told Italian media TMW: "Several teams are positioned on the player, but only the two Manchester teams, United and City, and PSG have been here to watch him.
"Have we received formal offers? No."
Despite having recruited a number of younger players from Italy in recent years, such as Federico Macheda, United have not made a major signing from Serie A since Juan Sebastien Veron's £28.1million capture from Lazio in 2001.