Scouts from Manchester United were in Croatia on Thursday to build up a report on S.L. Benfica defender Rúben Dias during the club's 1-0 defeat against Dinamo Zagreb.
The Portugal international has emerged as one of Europe's brightest defensive talents and is being eyed by a number of clubs across the continent.
With Manchester Unitedlooking to step up their pursuit of a new centre-back this summer, The Sunclaims that scouts were sent to the Stadion Maksimir to watch the 21-year-old in action before they consider a move at the end of the season.
Dias, who captained his side for the first time on Thursday, played the full 90 minutes as Zagreb's Bruno Petković scored the only goal of the game to give Benfica an uphill battle for the return leg at the Estádio da Luz next week.
Despite rightfully being dubbed as one of Europe's brightest defenders, Dias wouldn't have covered himself in glory in the eyes of Manchester United's scouts as he arguably had his worst performance of the season - conceding the penalty which lead to Petković's winner.
Dias was named as the young player of last season in the Primeira Liga, helping Benfica to a second place finish just seven points behind champions FC Porto.
Benfica are becoming accustomed to entering into transfer negotiation with teams in Manchester, having already sold defender Victor Lindelöf to United while goalkeeper Ederson joined Pep Guardiola's City.
While there hasn't been an asking price set in stone for Dias, it's suggested that a double deal which involves another Manchester United transfer target João Félix could be as high as £150m for Ole Gunnar Solskjaer's side.