Jadon Sancho was missing for Manchester United's friendly defeat to Atletico Madrid in Oslo.
The winger was forced after being laid low by a bug.
“Overnight he got sick, so he is not available," the Reds boss told MUTV.
Sancho has enjoyed a terrific run of form in pre-season, lethally scoring in victories over Liverpool and Crystal Palace.
He also netted a volley in the draw with Aston Villa last time out.