The 31 year old may be needed as emergency cover, like he was against Barcelona on Wednesday night.
United have something of an injury crisis at the back could provide emergency cover at the back for the start the new season with Jonny Evans, Phil Jones and Chris Smalling all currently unfit.
Ferguson told the club's official website, www.manutd.com: "Smalling is out for three months. Jones got a muscle injury in his back and was sent home from Norway, so the area we're concerned about is centre-back.
"Evans won't be ready for the start of the season. He won't be far away, but he won't be ready.
"Smalling is out and I can't give you an update with Jones because we've not fully diagnosed that.
"But Michael Carrick was absolutely brilliant [in Sweden] with his passing the ball and his interceptions. He was fantastic."
Source: FOOTYMAD
