With eyes on him from the stands, the centre-midfielder scored in his side's 3-2 victory over Portimonense.
The 26-year-old was apart of the Portugal squad that claimed the Euro 2016 trophy, which included starting in the semi-final victory over Wales.
At 6'2, Danilo has long been a target of Arsene Wenger, who has been searching for a physically dominant holding midfielder since Patrick Vieira left the club.
United boss Jose Mourinho reportedly keeps an interest in players from his former club.
Qatari-backed Paris Saint Germain have also been eyeing in the former Maritimo man.