Impressive McIlroy ramps up his challenge in convincing fashion

No let-up, no stopping. With each stride and each twirl of the club in self-admiration of another beautifully executed stroke, Rory McIlroy – who yesterday followed up an opening 66 with a second round 67 to reach the midpoint of this 96th staging of the US PGA here at Valhalla Golf Club on 133, nine-under-par – is venturing into the sort of golfing territory previously occupied only by the greats of the game.

Former world number one Tiger Woods dropped four shots in his first seven holes before carding a three-over-par 74 to make an early exit.

On a day which started with miserable, persistent rain – of which Shane Lowry could justifiably feel he experienced the short straw, being in the very first group forced to go forth in poor visibility on to sodden fairways and waterlogged greens – it was the world number one McIlroy, as he has almost routinely done of late, who found the capacity to marry a strong mental fortitude with an ability to craft the shots necessary to contend in his bid for back-to-back Major titles.

And, as he heads into the weekend intent on adding the Wanamaker Trophy to the Claret Jug he won in wire-to-wire fashion at Hoylake last month, McIlroy promised there would be no conservatism to his play.

"I've went into protection mode once in my career," he said, referring to the final round of the US Masters in 2011.

“That didn’t work out very well, so I said to myself, ‘I will never do that again’. I don’t think you can protect a lead, you just go out and play, to play your game and not think about the score.” Indeed, that final round experience at Augusta National three years ago has become a defining moment in McIlroy’s evolution. The meltdown has been recycled into a positive. “I think I’ve had to learn to be a good frontrunner. I wasn’t comfortable in that position at the start of my career, in 2009, 2010 and especially 2011, at the Masters . . . . it’s taken me a couple of years to grow into (being) comfortable. My mindset has stayed the same since that day at Augusta . . . . I’m just going to keep the pedal down and get as many ahead as possible.”

McIlroy's philosophy is one that has enabled him to shift up the gears this season, a year when he has also coped – remarkably well, it must be said – with his breakup with fiancée Caroline Wozniacki.

In the aftermath of that parting of the ways, McIlroy immediately won the BMW PGA Championship, the European tour's flagship tournament.

It was a portent of things to come, and in recent weeks has won the British Open and followed up with the WGC-Bridgestone Invitational.

“I think it has happened to me for the better. I’ve put a little more time into my golf and (it) refocused me in a way. I’ve just immersed myself in my game.

I’ve practiced hard and I’ve done all the right things. And I’m reaping the rewards . . . Golf is my number one priority and, while I’m on this run of form, I want to try and keep it going as long as possible. And I’m going to keep working hard and keep practicing and try and get even better. Hopefully, I can do that over the next few years and hopefully you’ll see golf like this more often from me.”

Clubhouse lead

McIlroy’s 67 for 133 enabled him to assume the clubhouse lead, two strokes clear of

Ryan Palmer

– who, playing with Lowry, had experienced a tough start to their second round when sent out on a sodden course by championship officials – and Rickie Fowler, while

Jason Day

was six-under through 16 holes.

On one point McIlroy was insistent: he would stick to his own game plan going into the weekend, be that as a frontrunner or chaser.

“I expect to execute my shots. I expect to do the things I can control. I can’t control the outcome. I can’t control what other people do. So, do I expect to win? No. But do I expect to do the things that I know I can do and control? Yes. And I know that if I do those well, there’s a good chance that I’ll win.”

The decision not to allow placing, following torrential rain, didn't go down well with a number of players. "We're playing the ball down, which in my book is not the best idea," claimed Henrik Stenson, with players complaining of mud balls. The respective plights of Lowry and Palmer also got sympathy from Vijay Singh, who opined: "It was almost unplayable on the driving range, getting those guys out on the first was a little bit unfair."

Lowry, in the first group off the first tee as the heavens opened, shot a second round 74 for level par 142 which at least enabled him to survive the cut into the weekend. “To be honest, we were playing the first hole, and it was a joke. You couldn’t see the flight of the ball after 150 yards. I called the referee and said it to him but he said ‘no, play on’. in the discussion, Lowry made the point to John Paramour. “You wouldn’t send Tiger Woods out in this.”