Mazraoui started the match but was forced to leave the pitch in the 69th minute after appearing to hurt himself while challenging Lesotho midfielder Neo Mokhachane.
The Manchester United defender appeared to land awkwardly following the challenge and required treatment before being replaced. The exact nature and severity of the injury have not yet been confirmed.
Mazraoui adds to United's injury concerns
The incident comes at a difficult time for Manchester United, who have already seen another defender, Patrick Dorgu, return to the club after suffering an injury with Denmark.
Dorgu was substituted after around 30 minutes of Denmark’s 2–0 Nations League victory over Wales on Sunday after appearing to suffer a problem to the back of his thigh.
Denmark manager Brian Riemer subsequently confirmed that the 21-year-old would leave the national-team camp and return to Manchester for further assessment.
Manchester United also confirmed Dorgu’s return in their latest fitness update.
Fernandes remains with Portugal
United captain Bruno Fernandes is another player currently dealing with a fitness concern.
Fernandes was left out of Portugal’s squad for their victory over Norway after playing 89 minutes against Wales.
Portugal head coach Jorge Jesus previously revealed that the midfielder had played through an injury in the Wales match. Despite the concern, Fernandes has remained with the national team and could still feature later in the international break.
United await Mazraoui assessment
For Mazraoui, United will now await further information from Morocco before determining the extent of the latest problem.
The 28-year-old had started Morocco’s AFCON qualifying campaign strongly, scoring in their 2–0 victory over Gabon in their opening Group A fixture.
His latest injury could therefore provide another headache for Manchester United manager Michael Carrick, with the club already monitoring the fitness of Dorgu and Fernandes.
Further medical examinations will be required before Mazraoui’s availability for Manchester United can be assessed.