Former Manchester United defender Paul McGrath has expressed his belief that the club must sign an experienced centre-back during the January transfer window.

United's lack of defensive options has come under the spotlight, with manager Louis van Gaal fielding youngsters Tyler Blackett and Paddy McNair in the 2-1 win at Arsenal on Saturday.

McGrath has claimed that his former side are desperate need of a leader at the back.

"Van Gaal will want money to spend," he told talkSPORT. "They badly need an older, more experienced defender.

"It's all about what you're allowed to spend and what players will come to the club. Man United could have let in a few more goals against Arsenal, they were fortunate."

The Red Devils are reportedly interested in signing Barcelona's Thomas Vermaelen on loan.