Rory McIlroy is hard. No, not just physically hard from all that tightening up of his body in the gym, but mentally hard. At least, that's how he feels.

Okay, he’s still liable to jump on twitter at the slightest criticism of the way he goes about his business though that might be humour given his aside that referenced TV analyst Brandel Chamblee. But in terms of having a killer instinct on the golf course, McIlroy says he’s feels less “guilt” about his rise to the top of the sport and now enjoys killing the opposition.

C HRIS REIMER: Do any squats today?

RORY McILROY: Not yet. I'm planning to, though. Maybe with Brandel on my back. (Laughter)

It will be interesting to see how he handles the test presented by Riviera Country Club, where his ball striking will be an advantage but his sometimes erratic putting stands up on poa greens he admitted take quite a bit of getting used to in this week's Northern Trust Open

With world No 1 Jordan Spieth a Riviera veteran by comparison, McIlroy plays his first ever PGA Tour event in the West Coast Swing on one of the most demanding courses around.

Given what he told the assembled media on Wednesday, he will be so fit for years to come that he may well play as many LA Opens as local favourite Fred Couples if he finds the course to his liking. Right now, that remains to be seen.

As far as attitude goes, McIlroy is now in pre-Masters mode and he appears determined to build on last year’s career-best fourth place at Augusta National, where he finally found a way of taking on the course.

Had he not been spooked by Spieth’s meteoric start, McIlroy might well have given the American a run for his money. He still appears a rung or two below the Texan in the confidence department, even if he does claim he’s now a far more clinical player at 26 than he was when he turned professional at the age of 18 in 2007.

“I definitely don’t struggle with it now,” he said when asked out his outright competitiveness. "I think it probably changed when I became more comfortable in my own skin and sort of knew who I was.

“There's a transitional period from being a teenager getting out on tour to your early 20s and you're still sort of discovering yourself and sort of knowing who you are and what you are.

"So I think somewhere in that time period, I learnt that it's okay to be a winner. It's okay to be selfish at times. It's okay to do these things. That's the reason that we work hard is to try and win these tournaments.

“So there was some -- because sometimes I still get those feelings of, I don't want to say I have guilt, but sometimes I feel like I haven't had to work as hard to get to where I am as some other people. 

"I don't know if that's guilt or if that's questioning why is that me; why am I the one that feels this way. But I feel now that I definitely have got a ruthlessness on the course that I maybe didn’t have a few years ago, but I never struggle that anymore.”

How hard McIlroy works off the course is something only he knows. He’s certainly intense at times but given his love of a happy off-course life and things away from golf, it would be understandable if he cut himself some slack.

The gym and fitness regime that drew some questions from Brandel Chamblee on Tuesday, provoking a twitter reaction from McIlroy, is something that McIlroy has bought into big time.

As Pádraig Harrington pointed out recently, US sports tend to be well behind the Europeans in terms of advances in sports medicine so it’s no surprise that images of McIlroy squatting 120kg might make a few wince.

Performance is one element but it's mainly done for injury prevention, of course, though a large Nike contract and a little natural narcissism is all the motivation a guy in his mid-20s needs to speed all those hours looking his own reflection in a gym instead of being out in the fresh air.

He explained it all in detail:

"Stay injury-free. That's really it. Obviously I'm trying to be strong but the whole reason I started this is because I was injured. Okay, I was injured last year but for a completely different reason.

You know, touch-wood, I've been fine since. I had a degenerative disk in my back that sort of stayed the same. It has not got any worse, for example. It's always been there. It's always been a disc that isn't quite as hydrated as the rest of them, but that's the golf swing.

You think of the golf swing and the torque and the load that you're putting on your spine. The spine does two things: It flexes and it rotates. And it doesn't like to flex and rotate at the same time, which is what a golf swing does. So if anything, the golf swing is way worse for your back than anything I do in the gym.

So I'm trying to make my back as strong as I possibly can so that when I come out here and swing a golf club at 120 miles an hour, I'm robust enough to take that 200 times a day when I hit shots and when I practice and when I play golf.

….They don't see the mobilisation exercises. They don't see the other stuff that goes into it, the warm-up. Not the real golf-specific stuff, but the things that you might only need a couple of dumbbells that weigh five pounds to do.

There's a lot of specific things in the golf swing that you need to strengthen and you need to have stable. And obviously the core, for me, I'm lucky because I was hyper-mobile before I started all this gym stuff. If anything, I needed to tighten my body up a little bit.

So that's why I can go in the gym and lift heavy-ish weights, for golfers, anyway. You look at other sports, I'm doing nothing compared to what those guys do, but I can get in there and I can try to get a little bit stronger because my body needs that nearly, and I want to get stronger in my core and definitely my lower back and my glutes and my legs, because I feel that's a huge foundation. And if I can maintain that and be strong in the right areas and be stable, obviously it helps my golf, but it will help me prolong my career to the point where I want to play and not have to end it prematurely because of not having looked after my body in the right way."

As for Riviera, he was full of praise for a course that member Mark Wahlberg, the actor, urged him to play when they met in Dublin last year.

McIlroy had already added it to his schedule at that stage on its reputation alone and he clearly relishes the challenge.

"Excited to be here. Played the back nine yesterday. Played all 18 today. It's a great golf course. We don't play golf courses like this very often anymore on tour, and it's a real treat when you come to a golf course like this where it's not overly long, you don't have to really bomb it off the tee, but it's real strategic. You've got to place your ball on the right sides of the fairways.

"You have to make sure you hit it to the right side of the greens. You really can't short-side yourself here. You can't really get it above the pin. It’s a real thinker’s golf course and it's a real treat to play something like this because we don't get to play them that often anymore."

Getting his game ready for the Masters is key as he plans to play five of the next six weeks and having struggled to hit the ball right to left in Dubai, where he was poor, he’s tweaked his drive to get more spin on the ball.

“I think the Masters at this point of the year is on pretty much everyone’s mind,” he said. "You're building up to it. You’ve got some great events in between now and then, but obviously I’d love my game to be in peak shape for Augusta in April… 

"There's a couple of things in Dubai I wasn't quite happy with, so I worked on those in Florida last week. I tweaked my driver a little bit. I felt like I was struggling to turn it over from right-to-left, so I put the loft up. I put the loft up a degree in the driver to help me spin it a little bit more to try and turn it over. And that was really it. I felt like the rest of my game was in pretty good shape, and tried to just — it’s different."

As for the tiny Riviera greens, he asid: "I practiced back in Florida, and putt over there, and then you get to these greens and it's completely different. It's poa versus bermuda. So I've spent quite a bit of time on the putting green the last couple of days, just trying to sort of get comfortable with them.

"Especially those, I think I saw a stat the other day, that there was more 3-footers missed here than there was anywhere else last year, I think by a long way actually. Inside sort of five or six feet is going to be really important this week, because you’re not going to hit the amount of greens that you're used to hitting. 

"You hit 12 greens around here, you've done pretty well. So there will be a lot of those holing-out-type distances for pars that will be important. I think that’s one of the big things this week for me, and I've been trying to work on that."