Manchester United have posted scouts to watch Feyenoord pair Orkun Kokcu and Santiago Gimenez.
The Mirror says United scouts were in attendance for the explosive KNVB Cup semifinal against Ajax last week. The tie had to be halted twice by the referee because of crowd trouble.
Tottenham, Brighton, Leicester, West Ham and Brentford were also represented.
United boss Erik ten Hag knows midfielder Kokcu from his time in the Eredivisie, while Mexico international striker Gimenez's form has brought him to the attention of major clubs across Europe.
The pair's impact this season has led Feyenoord to the top of the Eredivisie.
Gimenez, a 21-year-old Mexican international who was born in Argentina, has scored 23 goals in all competitions this season. He is the son of former Argentina international Christian Gimenez.