Fellaini went to ground clutching his left knee following a challenge from Arsenal's Sead Kolasinac during the first half of Belgium's eventful 4-3 triumph at the Grbavica Stadium. It was initially feared that Fellaini might be facing a long-term injury, but a scan on Sunday suggests a strain that might sideline the midfielder for a shorter spell instead.
But he will miss United's bumper Premier League clash with Liverpool and the next two weeks.
Belgium manager Roberto Martinez and the Belgian Football Association (KBVB) have confirmed Fellaini's injury that will keep him out for several weeks.
"We are all anxious about Fellaini", Martinez told reporters.
This means that United boss, Jose Mourinho will be without his ace midfielder when the Red Devils travel to Liverpool on Saturday.
Marouane Fellaini has been ruled out for at least two weeks after suffering a knee ligament sprain while on global duty.
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Marouane Fellaini has scored four goal for Manchester United in current season of Premier League.
But the giant Belgian ace will now miss the trip to Liverpool next Saturday.
"We fear that there's ligament damage."
Belgium have already qualified for the World Cup next summer and will play a dead rubber against Cyprus on Tuesday.