Louis van Gaal
Van Gaal is expected to be deprived of funds during the January window.Getty Images

Former Manchester United defender Paul McGrath has joined the growing list of ex-players advising manager Louis van Gaal to sign an experienced centre-back during the January transfer window.

United's injury crisis in defence has forced them to rely on youth pair Tyler Blackett and Paddy McNair at times this season, with Phil Jones, Jonny Evans, Chris Smalling and Macros Rojo having spent separate spells on the side-lines this term.

After United posted a 9.9% fall in revenue for the three months to September 2014, executive vice-chairman Ed Woodward claimed the club would not be entering the transfer market in the January window after spending in excess of £150m during the summer.

However, McGrath has become the latest former United player to observe that the club must improve their defensive ranks or risk relinquishing their place in the Premier League top four.

"It's all about what players will come to club," he told Talksport. "Van Gaal is in a difficult position at the moment and if you're going to spend most of your cash on strikers you're going to have a few problems at the back.

"Van Gaal will want money to spend [in the January transfer window]. Because United badly need an older, more experienced defender."

Another former defender, Gordon McQueen, said United should look to sign either Stoke City captain Ryan Shawcross or Swansea City and Wales skipper Ashley Williams in January, to strengthen a defence which has been much changed this season.

However, following a record-breaking summer of activity, with Angel di Maria arriving for a British record fee of £59.7m, United fans hoping for a January window of upheaval are set to be disappointed according to Woodward.

"We're not looking to enter the market for short-term fixes however we have targets that we are looking at for next summer," Woodward said.

"Should any of those become available in January, which is obviously rare, we will consider acting. We have to accept that that is a low probability."