Darren Clarke was Mr Sunshine again as he gave his Ryder Cup hopes another massive boost by opening with a five under par 66 at sun-splashed Killarney.

The big Ulsterman, famous for his grumpy moods when things aren’t going well, teed it up with Rory McIlroy in a tournament for the first time and outscored the young superstar by a shot.

Chipper Clarke, 41, rolled back the years with a sensational display of ball-striking as he hit all 18 greens and rolled in five birdie putts to trail leader David Howell by just two shots.

Boosted by Wednesday’s special invitation to play in next month’s US PGA, Clarke beamed: “I’m obviously trying to play very, very well and get further uplifts so it was a great bonus to hear that they had given me the invite.  

“I was delighted to get one and it was certainly a great boost before the tournament started.”

It was a superb opening morning for Ireland’s big guns as Paul McGinley weighed in with a three under 68 that could have been even better had it not been for a three-putt bogey at the last.

But no-one was happier than Clarke - named as one of Colin Montgomerie’s Ryder Cup vice-captains last week - as he continues his golfing resurrection.

McIlroy has known his mentor for close to a decade but he has rarely seen his fellow Ulsterman as upbeat and he’s delighted to see him coming back to form.

McIlroy said: “He’s playing very, very well at the minute.  He’s on a nice run of form and his confidence is up from getting into contention at Loch Lomond and playing in the Open at  St Andrews and playing quite nicely, playing with Tiger on Saturday.  

“I think he’s happy at the minute.  He’s going to be moving home in the next couple of weeks back to Portrush. He got the Ryder Cup vice captaincy and I think he’s just enjoying himself.”

Clarke’s mood is usually linked to his success with the putter and while he’s not putting the lights out, he’s holing out brilliantly under pressure.

Despite predictions that someone could shoot the European Tour’s first 59 this week, Clarke knows that having patience on the undulating greens is going to be key to his bid for his first Irish Open win.

After draining a double breaking six footer for par at the last, Clarke said: “Sometimes you’ve got to take your chances when you hit it close around here, and I did that most the time today.  

“The greens are so undulating -  you’ve got double breaks, three breaks going on all over the place - you have to make the most of it.  

“But putting around here is tough and you’re going to see so many guys missing putts because it is so difficult to actually read the greens right.  

“Putting is something that I think you’ve got to be very patient with and as you’re all aware, that’s not really one of my strong points. Hopefully I am getting much better at that.”

Patience hasn’t always been McIlroy’s strong suit either but he showed it in spades yesterday as he bounced back from a rough patch in the middle of his round to stay in touch with the leaders with a four under 67.

Clarke said: “If you start chasing birdies out here, you’re going to start making mistakes.  And that’s what happened with Rory today, he made a couple of little mistakes and the course jumped up and bit him.

“Having said that, he finished off brilliantly to get himself back up there again.  That’s just the way the golf course is.”

Four under par through the first seven holes, world No 8 McIlroy dropped three shots in the next six before picking up three birdies coming home.

Surprised by the massive crowds that turned up for his early morning threeball with Clarke and Rhys Davies, McIlroy said: “I don’t think I’ve ever seen so many people on the first hole for an eight o’clock tee time before.  It’s fantastic.

“It was a good day.  I made plenty of birdies and a few bogeys but to shoot 67 the first round is a good start and a score to build on.

“It could have been a couple of shots better, definitely, but it’s still a nice way to start, and as I said, it’s a score that I can hopefully improve on the next three days.

“I had got it going and then dropped three shots in the space of a few holes, and it was nice to get those back in the last few.  It will make lunch taste a little bit better today.”

Ryder Cup vice captain McGinley, 43, scorched to five under after seven holes by following birdies at the second, third and sixth with a sensational eagle three at the seventh.

Playing into the sun, the Dubliner didn’t even see his shot of the day - a 214-yard four-iron that stopped just a foot from the holes.

Even with a bogey at the ninth, he turned in 31 but he stalled on the way home by following eight straight pars with a three-putt bogey at the last after overshooting the green from a fairway trap.

Still recovering from his sixth knee surgery, McGinley said: “I got off to a great start but the rest of the round I didn’t play great.

“Obviously the last was disappointing.  Just coming right over the hump right there, it was a difficult first putt and I thought I hit a good second putt but obviously I misread it.

“I’m not putting any pressure on myself. I didn’t play fantastically well but I played nicely and I’m looking forward to the rest of the week.”

What pleased McGinley even more than his score was the scorching summer weather.

He grinned: “It’s about time.  That’s all I can say.  We have been dogged with bad weather for the Irish Open, and we all know the weather is not as bad as it’s been every time we come here.  

“Hopefully it will stay like this for the weekend because there will be great crowds if it does.”