Former champion Rory McIlroy hailed one of his best rounds ever in the Open Championship after remaining in contention for a fifth major title at a windswept Royal Birkdale.

McIlroy was five over par after six holes of his opening round and seemed destined for a fourth missed cut in five events until a stern talking to from caddie JP Fitzgerald prompted a back-nine rally.

The world number four came home in 32 with three birdies in the last four holes and maintained that momentum on Friday, despite far tougher conditions for the morning starters.

Birdies on the first, third and sixth helped McIlroy reach the turn in 31, eight shots fewer than on Thursday, and although he dropped shots on the 13th and 15th, a birdie on the 17th helped the 28-year-old complete a superb 68.

"That's right up there," said McIlroy, who equalled the lowest score in major history with an opening 63 at St Andrews in 2010 and opened with consecutive 66s on his way to victory at Hoylake in 2014.

"It's really tough out there. I was lucky enough to get off to that great start but conditions got a little worse on the back nine. This south-east wind is the toughest on this course and I made a couple of bogeys, but really pleased to birdie 17."

At one under par, McIlroy was just three shots off the clubhouse target set by American Matt Kuchar, who could only add a 71 to his opening 65, with Scotland's Richie Ramsay on two under par after an excellent 70.

"I thought if I could keep it under par for the championship I am right there for the weekend," McIlroy added.

"I went out and believed in myself from the first tee shot, hit it within 60 yards of the green and went from there. I saw a lot of quality out there which was good.

"I just wanted to continue with that good feeling from the last few holes (on Thursday) and went out with that positivity and trust in myself and just need to keep that for the next two days. I cant wait."

Playing alongside Kuchar, Ramsay - who qualified by finishing second in the Irish Open which benefits McIlroy's foundation - carded 16 pars, one birdie and one bogey to add a 70 to his opening 68.

"It was some of the best golf I have played this year and I am just loving being out there," the 34-year-old from Aberdeen said. "It's easy to say when you are playing good golf, but with Rickie Fowler in the group in front of us and Matt doing well the atmosphere was brilliant."

Speaking about his elevated position on the leaderboard, Ramsay added: "It's pretty cool isn't it? You grow up and practice having a putt to win the Open.

"I'm in a position to compete for it which is something I have needed to do to tick a box, to compete with the best players in the world. Whether I do that the next two days I don't know, but I have to give 100 per cent and try to be the best I can be and take it from there."

Only four sub-par rounds were recorded by the first 60 players, with 2015 champion Zach Johnson carding a brilliant 66 to move 94 places up the leaderboard and reach one over par.

Fellow American Jamie Lovemark was level par after a 69, with Sergio Garcia on two over after returning the same score, despite injuring his shoulder after lashing out at a gorse bush on the fourth.