Manchester United boss Jose Mourinho reportedly made a personal check on Axel Witsel during Belgium's UEFA Nations League clash with Iceland on Friday night.
Mourinho's attendance for the international match was put down to Toby Alderweireld's presence as United consider a swoop for the Tottenham Hotspur centre-back.
However, according to Het Laatste Nieuws, Mourinho was actually watching Borussia Dortmund midfielder Witsel as United eye a move for the 29-year-old.
Witsel, who spent the 2017-18 campaign with Chinese outfit Tianjin Quanjian before returning to the European game, has a contract with Dortmund until the summer of 2022.
The midfielder has scored three times in 17 appearances for his German club this season.