The Iron's Under-18 side were beaten 4-1 at home by their Lincoln City counterparts on Saturday morning in their final game prior to Christmas.
"As much as we were pleased the other night at Manchester United. we're as disappointed today," said academy manager Tony Daws.
"We just weren't at the races and today out of possession we weren't good enough in terms of regaining the ball, closing down, pressing, tracking and keeping the ball out of our net.
"Then in possession we weren't good enough in terms of retaining it, moving the ball up the pitch and creating goalscoring opportunities.
"We were off it and it was probably our worst performance of the season, but Lincoln deserve credit as well because they're a good side with a decent bunch of lads, who are flying high in the league."
United's consolation goal came towards the end from Harrison Poulter, who got on the end of a cross from the right-hand side, sliding in to bundle his 11th goal of the season over the line.
Scunthorpe had a couple of other chances late on and return to action on Saturday, January 8th with a trip to Doncaster Rovers.
IRON: Balme, Wallace, Baker (Moore, 65), Strouther (Young, 45), Elliott-Bell, Pike, Franklin, Robertson (Cribb, 65), Poulter, Wilson, Moore-Billam (Sellars-Fleming, 63).