Eagle-eyed Manchester United fans spotted what Willy Kambwala was doing on the touchline ahead of his cameo appearance against Arsenal at Old Trafford on Sunday. Willy Kambwala has impressed since his emergence from the Manchester United youth academy and received his senior call-up under Erik ten Hag. The 19-year-old broke into the United first team in the current campaign and Kambwala has been building valuable experience with sporadic playing time. Kambwala has made eight Premier League appearances for the Red Devils this season, with the United defender making three starts under Erik ten H…