Marcos Rojo suffered a possible injury setback on his return to action with Manchester United's Under-23 side on Friday.
Argentina defender Rojo's last competitive action came in his country's 4-3 defeat to France in the last-16 of the World Cup.
United boss Jose Mourinho told reporters earlier in the day that he hoped Rojo and close-season signing Diogo Dalot would be able to complete 90 minutes and show they are ready for first-team selection.
However, Rojo limped off after 54 minutes of the 1-1 draw against Reading.
U23s: FT - 1 Reading 1. Josh Bohui's 66th-minute strike from Zak Dearnley's low cross earns a point for the Reds at Old Trafford. Diogo Dalot completed 90 minutes, Marcos Rojo played for 55. September 14, 2018
United Under-23s boss Ricky Sbragia later told MUTV Rojo would be "okay" after spending time with the club's medical staff.
Dalot played for the entirety of the contest as United's Joshua Bohui cancelled out Ben House's early opener for the visitors.
