Manchester United have stepped up their interest in Monaco pair Kylian Mbappe and Tiemoue Bakayoko, having sent head scout Marcel Bout to assess the two players during the 3-1 Champions League victory over Manchester City on Wednesday, sources have told ESPN FC.

Real Madrid and Barcelona are also monitoring 18-year-old Mbappe, who opened the scoring in against City, while Pep Guardiola's City are admirers of defensive midfielder Bakayoko, whose late header secured Monaco's progress.

United manager Jose Mourinho has made attacking reinforcements a priority this summer with Wayne Rooney expected to leave Old Trafford, while a long-term successor for Michael Carrick is also being sought and Bakayoko, 22, had already been on his radar.

Bout, who arrived at United in the summer of 2014 as Louis van Gaal's chief opposition scout, remained at the club following the former Netherlands boss' dismissal at the end of last season and was given a more senior role by Mourinho within Old Trafford's scouting department.