Cape Town - Manchester United's first team squad returns to training on Monday but they do so without Argentine duo, Angel Di Maria and Marcos Rojo.
The Independent report that Manchester United are waiting to find out the extent of Angel Di Maria's hamstring injury.
The club's record signing limped off during Saturday's Copa America final against Chile - a match which saw the Chileans seal a 4-1 penalty shootout victory after neither side were able to find the back of the net.
Manchester United manager Louis van Gaal had previously stated that both Di Maria and Rojo would be given extra time off should Argentina progress deep into the South American showpiece but Di Maria's injury now threatens to derail the start of a crucial second season for both player and manager.
The Old Trafford giants play their first leg Champions League qualifier on either Tuesday August 18 or Wednesday 19 August, with the return leg a week later. Both Argentines would be listed as doubts to feature in those matches.
The rest of the first team squad due at Manchester United's Carrington base today, including the club's number one goalkeeper David De Gea.
De Gea has been the subject of intense transfer speculation in the early part of the summer transfer window but an official bid from Real Madrid has yet to be lodged.
The Red Devils jet off to the USA on July 13 for their pre-season tour.