Kobbie Mainoo, Dan Gore, Isak Hansen-Aaroen and Omari Forson are 'frequently' training with Manchester United's first-team.
United's 21s started their Papa Johns Trophy campaign with a 2-1 win over Carlisle at Bruton Park on Tuesday night. Charlie McNeill, 18, and Forson, 18, were on the scoresheet and United did well to respond to Carlisle finding an equaliser in the second half.
Travis Binnion, who normally manages the U18s, was on the touchline for the match instead of coach Mark Dempsey and he led United to FA Youth Cup success last season, with Mainoo, Hansen-Aaroen and Gore playing key roles in that triumph.