Two early goals from Matt Done set the scene for United's latest win.
Played at the picturesque La Manga Club in Spain, Chris Wilder's side cruised to a success over a Murcia Region Representative Squad. Jake Wright and John Fleck made their debuts.
Done, who also scored twice in Saturday's victory over Stocksbridge Park Steels, netted his first with a chip after just four minutes. He added a second just five minutes later after a defensive mistake.
Despite chances from Fleck, Scougall and Whiteman, the Blades were unable to extend the advantage until a minute after half-time when Calvert-Lewin was fouled and Sharp netted from the penalty spot.
Sharp added his second on 64 minutes with an impressive volley from a deflected Coutts cross before Moussa reduced the arrears on 67 minutes with long-range effort.
The Blades had plenty of chances to extend the lead - O'Connell had a header cleared off the line and Duffy went close before Sharp had three chances to claim a hat-trick, including hitting the crossbar on 80 minutes.
The final chance, on 86 minutes, saw Reed head wide a Brayford cross at the back post.
Blades 1st half: Eastwood, Freeman, Hussey, Wilson, Wright, Whiteman, Fleck, Scougall, Adams, McNulty, Done.
Blades 2nd half: Ramsdale, Brayford, K. Wallace, O'Connell, Whiteman, Basham, Reed, Coutts, Duffy, Calvert-Lewin, Sharp.