The United striker missed Saturday's 4-3 win over Bosnia-Herzegovina in Sarajevo as a result but Martinez has now declared the player is "100 per cent" fit to face Cyprus. We are in touch with Man United's medical team.
United's other matches are the away games at Huddersfield Town in the Premier League and Swansea City in the Carabao Cup, before the league visit of Tottenham Hotspur and the return match against Benfica.
Speaking ahead of tonight's qualifier against Cyprus, Martinez said: "Marouane, it has been confirmed that he has got ligament damage".
Jose Mourinho is certain to be livid after hearing that one of his key players will be sidelined for an extended period, which includes missing their crucial clash against Liverpool on Saturday (14 October). "He has gone back to Manchester United", Martinez said, as quoted on Sky Sports.
Despite having endured an underwhelming first four seasons at United, Fellaini has proven himself to be invaluable to the club with Mourinho favouring height.
The 25-year-old has formed a strong defensive partnership with Eric Bailly this season and Mourinho will be anxious that he makes the weekend trip to Anfield.
"But there was nothing wrong in that respect so the relationship is very, very good with Manchester United as you would expect".