Rory McIlroy admits the back nine caught him by surprise on day one of The Open.

The Northern Irishman struggled at Royal Troon with a final-round score of +7 par 78.

It was far from vintage from the world ranked number two as he gave himself a stringent second-round task, with little to no margin for error if making the cut is to be achieved.

One stat he’ll definitely not want to see if that, since 2000, only 5.6 percent of players who shoot 78 or higher in round one of The Open have come back to make the cut. Sorry, Rory.

He’ll not go down without a fight though, with four-time major champion proving in the past that he can claw things back.

“I felt like I did okay for the first part of the round and then missed the green at the Postage Stamp there and left it in and made a double,” said the 35-year-old. “But still, felt like I was in reasonable enough shape being a couple over through 9, thinking that I could maybe get those couple shots back, try to shoot even par, something like that. Then hitting the ball out of bounds on 11, making a double there.

“ Even though the wind on the back nine was helping, it was a lot off the left. I was actually surprised how difficult I felt like the back nine played. I thought we were going to get it a little bit easier than we did. The course was playing tough. The conditions are very difficult in a wind that we haven't seen so far this week.

“I guess when that happens, you play your practice rounds, you have a strategy that you think is going to help you get around the golf course, but then when you get a wind you haven't played in, it starts to present different options and you start to think about maybe hitting a few clubs that you haven't hit in practice. Yeah, just one of those days where I just didn't adapt well enough to the conditions.

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“I just think that your misses get punished. Your misses get punished a lot more this week than even last week or even, geez, any weeks, whether you miss it in a fairway bunker or even the rough. The rough, the balls that I hit in the rough today, the lies were pretty nasty. I think it's more you just get penalised more for your misses.”

Bryson DeChambeau also suffered an opening round to forget. The American was five over for the day.

The 30-year-old got off to a nightmare start with four bogeys and a double-bogey on the front nine. He recovered well enough to finish strongly with a -1 score on the back nine, giving him a total of 76 for the day.

He commented on his early issues: “It was in and off the right and I was trying the draw the ball and the ball was knuckling a little bit. It was a really difficult challenge, and I should have just cut the ball.

“It's a completely different test (from practicing). I didn't get any practice in it, and I didn't really play much in the rain. Yeah, it's a difficult test out here.

“Something I'm not familiar with. I never grew up playing it, and not to say that that's the reason; I finished eighth at St Andrews. I can do it when it's warm and not windy.”

Fellow American compatriot and legend of the game Tiger Woods finished eight over.