Colin Montgomerie believes 'negative thoughts' impacted Rory McIlroy's unsuccessful quest for US Open glory on Sunday, with Bryson Chambeau winning the prestigious competition instead.

McIlroy was two shots ahead with just five holes to go but ended up missing out on glory, with Chambeau capitalising to win a second major of his career.

The 35-year-old was left devastated by his defeat and made a swift exit from Pinehurst.

It has been 10 years since McIlroy last won a major, with his last major victory coming at the PGA Championship in 2014.

And Montgomerie, who surrendered a two-shot lead with four holes to play at the US Open in 2006, believes 'negative thoughts' impacted McIlroy in the closing stages.

“If he doesn’t win another major this will stay with him," he told the i newspaper.

"I really felt for him leaving the club last night.

"A lot of the media were saying he should have stayed for the press conference and stuff, but I understand as a player. He walked out with dignity, quite slowly and dignified.

"He was okay through 14 but at the end there I think the 10 years of not winning a major were weighing heavily on his mind.

"He hit the wrong club on 15, to go big there was unfortunate and where he finished was unlucky.

"The 16th was the killer, to hit two great shots there and then three putt.

"He had 496 putts in a row inside three feet and then he misses one on the 70th hole of a major. That says a lot to me, unfortunately.”

He added: "It’s amazing how many negative thoughts can swim through one’s mind.

“Rory’s errors can only be put down to negative thoughts."

Montgomerie also agrees with Nick Faldo's assessment that his implosion at Pinehurst could haunt McIlroy for the rest of his career.

“As Nick Faldo rightly said in the commentary, this will haunt him for a while and could haunt him for a lifetime," he opined.

“Let’s hope it doesn’t. Let’s hope he can come to Royal Troon for The Open and do well.

“But winning now after what’s happened again, again, again over the last ten years. We’ve said this. It’s hard for him.”

While McIlroy was left crushed by his defeat, Chambeau is one person who thinks the Northern-Irishman has what it takes to bounce back.

“Rory is one of the best to ever play,” said the 30-year-old.

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“Being able to fight against a great like that is pretty special.

"For him to miss that putt, I’d never wish it on anybody. It just happened to play out that way.

“He’ll win multiple more major championships. There’s no doubt. I think that fire in him is going to continue to grow.

“I have nothing but respect for how he plays the game of golf because, to be honest, when he was climbing up the leaderboard, he was two ahead, I was like, Uh-oh, uh-oh. But luckily things went my way today.”