Manchester United have triggered a clause in Marouane Fellaini’s contract that will keep him at Old Trafford until 2018. Fellaini signed a four-year deal with the option of a further year when he joined from Everton for £27.5m in 2013. United boss Jose Mourinho has activated the option despite uncertainty over the 29-year-old midfielder’s future. Fellaini was booed by his own fans last month but scored in the EFL Cup semi-final win against Hull on Tuesday.