RTÉ soccer analyst Eamon Dunphy has dismissed talk of Manchester United being Premier League contenders, saying "reason seems to have gone out the window” in response to United’s 4-0 win over QPR.

After a disappointing first three Premier League games under new boss Louis van Gaal, United were utterly dominant against QPR, with their new attacking signings to the fore as the put the Londoners to the sword.

After the game Van Gaal said he was targeting the Premier League, but Dunphy suggested United were still not of the quality needed for win the league, and that their defence, in particular, would cause them problems.

"If you look at the back four, Rafael, Jonny Evans, Tyler Blackett and [Marcos] Rojo: if that back four ever plays against a proper team, they’ll be murdered," he told RTÉ Sport.

Dunphy also suggested that Sunday’s 4-0 scoreline was a result of good fortune and a particularly weak QPR.

"If you look at the goals: the first one was an accident," he said.

"It was a good free kick but it wasn't meant to be a goal. The one that Di Maria allegedly made was a shot which he mishit, and because of Rio [Ferdinand's] inability to walk, Mata was able to score. So, it you break down to its constituent parts, it was quite unimpressive, really."

Dunphy said that some of United recent acquisitions were world-class, but that overall, the squad were not good enough to challenge the likes of Chelsea and Manchester City.

"They have Falcao, who is an amazing player – if he's fit, and we have to find that out, yet," he said. "But they’re nowhere near it."

"Rafael, Jonny Evans, Tyler Blackett and [Marcos] Rojo: if that back four ever plays against a proper team, they’ll be murdered" - Eamon Dunphy

Dunphy said United had panicked in their purchasing over the Summer transfer window, and although he conceded they had got some world-class players, he contrasted this with other squad-members who he did not rate so highly.

"There was a lot of panic buying: [Daley] Blind, they bought him for £16m. I mean, if he was that good he wouldn't be costing that price," he said.

"Di Maria is a real acquisition: he’s got pace and his commitment is brilliant, and he’s a proper top-class player.

"And they have of course got Rooney and Van Persie – who didn't look great [on Sunday], Van Persie.

"They have Falcao; now Falcao is over his cruciate ligament problems. They have him for a year on loan. He could be as Diego Costa is at Chelsea: a real factor.

"But they have some desperate players as well. I mean, Tyler Blackett, Rafael, Jonny Evans and the left-back they've bought, the Argentinian, Rojo – he’s hoho – he’ll be killed, they'll be killed when they play a proper team. And it’s coming up: they've got to play Chelsea in the not-too-distant future.

"When you buy a group of players – I think Van Gaal has six or seven players to integrate into a team – first of all you've got to make them into a team. No matter how good they are that takes time.

"[Next], he has to get a defence from somewhere, and he doesn't have one. They were nearly a goal down [against QPR]. If that defence, that back four plays against any team, and I don’t mean Chelsea or Arsenal, I mean if they play against any half-decent team, they’ll be beaten.

"No matter how many great forwards you've got you have to have defenders."