Manchester United are hoping to prise teenager Umaro Embalo away from Benfica, sources have told ESPN FC.
Chief scout Javier Ribalta and head of development John Murtagh watched Embalo, 16, during Benfica under-19s' UEFA Youth League tie with United in Lisbon on Wednesday.
Embalo came on as a second-half substitute as United, managed by academy chief Nicky Butt, came back from two goals down to draw 2-2.
Joshua Bohui got both goals for United, who had Butt sent to the stands and attacking midfielder Indy Boonen sent off after the final whistle.
United have been following Embalo, who can play as a winger or a striker, for almost a year.
However, sources have told ESPN FC they are not the only club interested in the youngster, who was born in Guinea-Bissau but represents Portugal, and face competition from a number of European heavyweights.
United are also tracking two more of Benfica's impressive U19 side.
Club scouts in Portugal are keeping a close eye on 17-year-old forward Joao Felix, while 18-year-old midfielder Joao Filipe has spent time on trial at Carrington.
Felix, who has already represented Benfica B and been called up by Portugal's U21s, is rated as one of the country's top prospects.
Both Felix and Filipe were part of the Benfica team which reached the final of the UEFA Youth League last season.
The Portuguese side are keen to keep hold of their most exciting young players and tied Filipe down to a new long-term contract in August that could keep him at the club until 2022.
However, sources have told ESPN FC that after spending time training with United earlier in his career, he would welcome renewed interest from Old Trafford.