Man United news: Medical expert reveals how many weeks Fred now set to miss - 'It's a real worry'
Fred could be out for as long as four weeks - a worrying scenario given the injury problems Man United currently have in midfield.
That is the view of injury expert Ben Dinnery, who runs the Premier Injuries site and has a background in medicine and data analysis.
Fred, 29, was forced off before half-time in the Red Devils' 1-0 defeat at Everton last Saturday (9 April).
As quoted by club media after the match, interim United boss Ralf Rangnick revealed that the Brazilian midfielder had suffered a "hip flexor" issue.
Scott McTominay, often Fred's partner in the middle of the park, did not feature in the clash at Goodison Park through a foot injury.
Dinnery gave a best-and-worst estimation of how long Fred is set to be out.
"As with any muscular problem, severity is key," he told Football Insider's Adam Williams.
"If we are looking at something relatively minor, we could be talking seven to 14 days. As the level of severity goes up, the longer he would be out.
"If it was just a little tightness and it was more a precautionary measure, maybe there is an outside chance of him being involved this weekend.
"Imaging will determine the severity of the problem. But if it is more severe, that can easily extend to three to four weeks.
"It is a worry given what else is happening within that Man United team, with McTominay and others."
Fred has chipped in with four goals and six assists in 33 outings in United colours this term.
This site revealed on Monday (11 April) that United will trigger Erik ten Hag's Ajax release clause after deciding to make him their new manager.