MANCHESTER, England - Manchester United midfielder Michael Carrick was ruled out for about four weeks on Friday, just as another of manager Louis van Gaal's vice-captains prepared to end his 12-year stay at Old Trafford.

Carrick has a muscle injury and could miss up to six games, depriving the team of a player who has been instrumental in its improved results since November.

The England international has shored up United's midfield since returning from a long-term injury during the 1-0 loss to Manchester City on Nov. 2. United has lost only once in 14 games since then, and is fourth in the English Premier League heading into Saturday's home match against Leicester.

Van Gaal also said Darren Fletcher, who like Carrick is a deputy to captain Wayne Rooney, is at West Ham ahead of a potential move to Upton Park. The Scotland midfielder has struggled for first-team opportunities under Van Gaal.

Fletcher made his United debut in 2003, and has played 342 times despite missing almost two years due to ulcerative colitis, a debilitating illness.

"He is an important guy in the dressing room. I like him as a human being and as a player. We shall miss him," Van Gaal said.

"But he has not played so many times; always that is the main goal of a player. We have talked about that. He prefers to play. Therefore, we have helped him to go away. For us, it is a miss, a loss."

United announced the signing of 20-year-old right back Sadiq El Fitouri from local side Salford City, which is co-owned by former United stars Gary Neville, Phil Neville and Paul Scholes.

The Libya-born El Fitouri, who spent time at Manchester City as a teenager, made his debut only in December for seventh-tier Salford, and impressed during a week's trial at United.

He has signed an 18-month contract and will start in the United Under-21s.