Paul McGrath says Manchester United boss Louis van Gaal needs to buy a defender in January.
The former United defender sees the need for a centre-half as a priority.
"Van Gaal will want money to spend [in the January transfer window],"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."
