Manchester United have renewed their interest in West Ham teenager Domingos Quina, with scouts watching the 17-year-old score for Portugal under-19s against Spain this week, sources have told ESPN FC.
Quina, who was born in Guinea-Bissau but represents Portugal, is regarded as one of the brightest young prospects in Europe.
He joined West Ham in 2016 after spending three years with Chelsea's academy.
United, Arsenal and Paris Saint-Germain all considered a move for Quina before he signed for West Ham, but with the midfielder yet to commit to a long-term contract United have stepped up their scouting of him.
Quina's current deal at West Ham expires in 2019 and talks aimed at extending it began last month.
He has made two senior appearances for West Ham this season, both as a late substitute in Carabao Cup ties.
But the arrival of David Moyes as manager has raised concerns over the prospect of further first-team opportunities with the club struggling in the Premier League.