Manchester United reportedly watched Benfica pair Ruben Dias and Joao Felix up close during Sunday's Primeira Liga clash with Braga.
The Red Devils have been linked with the young duo in recent weeks and are rumoured to have now stepped up their interest in both.
Dias is a 21-year-old central defender and Felix, touted as one of the hottest talents on the continent, a 19-year-old forward.
Portuguese newspaper O Jogo reports that United sent chief scout Marcel Bout to watch the players in action against Braga - a match Benfica won 4-1, with Dias on the scoresheet.
The wheels are already in motion for United in terms of their summer transfer plans, with young, hungry players being targeted to help bridge the gap on Manchester City and Liverpool.
Felix has netted 18 goals in 40 appearances this season, while Dias has helped the Eagles to clean sheets in half of his 30 league outings in 2018-19.
