"I was so happy to join United," Fellaini told reporters at his first news conference, according to Charles Perrin in the Express. "I came here to win trophies. For me it's a dream to join the biggest club in the world."
However, Fellaini saw his former club finish two places above his new club in the 2013-14 season.
The closest United came to winning a trophy was playing in the League Cup semi-final, where they were beaten by Sunderland on penalties.
Fellaini is now representing his country in the World Cup and has played every minute since coming on as a substitute to score in Belgium's first game.
However, Ian Ladyman of the Daily Mail reported on Wednesday that Louis van Gaal has no interest in giving Fellaini a second season at United.
If Fellaini is set to leave this summer, what have been some of his worst moments at the club?