The Premier League champions are also interested in signing Leighton Baines from Everton and are considering whether to offer around £30m for the pair.
Moyes, who has so far added only the young Uruguayan full-back Guillermo Varela to his squad before his debut season at Old Trafford, worked with Fellaini and Baines at Goodison Park, having signed the former for £15m from Standard Liège in 2008 and the latter for £6m from Wigan Athletic in 2007.
Roberto Martínez, who has taken over from Moyes at Everton, has said that the club have yet to receive an offer for either player and Moyes is acutely sensitive about the need to conduct any business with his former employer in the right way. His respect for Everton, where he worked for 11 years before succeeding Sir Alex Ferguson, runs deep. But he is clear about the merits of both Fellaini and Baines and he is poised to make his move for them.
Fellaini is understood to have offers from elsewhere in the Premier League but he would relish the opportunity to join United and continue his working relationship with Moyes. The 25-year-old's contract at Everton contained a £23.5m buy-out clause but it expired on 31 July, meaning that his value will now be determined by market forces.
United's need for reinforcement in midfield has been intensified by Paul Scholes' retirement at the end of last season and Moyes has pushed to take Fábregas, the former Arsenal captain, seeing two bids turned down by Barcelona. United have also been linked with a move for Luka Modric of Real Madrid although that, too, has been fraught with complications.
Arsène Wenger, the Arsenal manager, has said for the past three weeks that his information is that Fábregas will stay at the Camp Nou for at least another season. Despite the disappointment of Fábregas's departure from Arsenal in 2011, Wenger continues to have a good relationship with him while the player's agent is the son of David Dein, Wenger's closest contact in the game.
In this summer of the contractual transfer clause Arsenal have one that effectively entitles them to first refusal on Fábregas. Wenger's information would appear to be well-sourced. The Barcelona sporting director, Andoni Zubizarreta, also said at the weekend that United had "renounced" the signing of Fábregas. "They understand our position of not wanting to sell," Zubizarreta said. "We aren't going to sell him."
Fellaini is a different type of midfielder, with reservations over his passing ability and disciplinary record. But the Belgium international has skill, tremendous presence and goal threat, as evidenced by his 12 goals for Everton last season. One of them was the winner against United in the opening round of matches.
Baines would provide competition to United's current left-back, Patrice Evra, who has given excellent service since his £5.5m move from Monaco in 2006. The 28-year-old Liverpudlian, capped 17 times by England, has become the model of consistency and Martínez, who rates him as the best left-back in the country, does not want to lose either him or Fellaini. Everton rejected a bid of around £12m for Baines from United in June.
"There are no bids," Martínez said. "When you read that someone is interested in someone, it doesn't mean there is a bid on the table. Marouane has been working really hard. Leighton Baines has been working really hard for the team, and that's all that matters. I've said from day one as a manager you only concentrate on working hard. I don't mind having my players grabbing headlines. That's a good story because it means they've been doing well. I'm only concentrating on having as strong a squad as possible for the start of the season."
Moyes remains confident of adding to his squad. "I do think we'll be bringing players in before the window shuts," he said after United's 1-1 friendly draw against AIK in Stockholm. "They will come. We're moving along but if you said, 'Is anything close?' I couldn't give you an answer."
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