OAKMONT, Pa. — Ever since Rory McIlroy checked the biggest box off his impressive golf to-do list, all he wanted was to enjoy it.

Very quickly, he has discovered how harsh this game can be with his foot off the gas.

Heading into the US Open this week, McIlroy has been disabused of any notion that life once he completed the career Grand Slam with that win at the Masters in April would be smooth sailing.

"I think it's trying to have a little bit of amnesia and forget about what happened," McIlroy said Tuesday when asked about the difficulties he has faced — on the golf course, at least — since donning the green jacket. "Then, just trying to find the motivation to go back out there and work as hard as I've been working."

That edge has been tough to rediscover, buried somewhere beneath the satisfaction of finally conquering Augusta National to become only the sixth player to win all four majors in his career. He has celebrated by taking more trips, playing more tennis, hanging out at home and "basically saying 'no' to every request that comes in".

His forays back to his day job — rough.

McIlroy arrived at the PGA Championship a month after the Masters only to learn that the driver he'd been using for more than a year had been deemed nonconforming in a routine test.

He hit only 46.4 percent of the fairways that week, tying him for 68th out of 74 players in that statistic who played four rounds. Those struggles with the new driver made him a non-factor and he finished tied for 47th.

"It wasn't a big deal for Scottie, so it shouldn't have been a big deal for me," McIlroy said, noting Scottie Scheffler received the same news about his own driver that week but went on to win the tournament.

That the normally closely held news of McIlroy's illegal driver leaked to the media and Scheffler's did not annoy McIlroy, and he said last week that was why he didn't speak to the media after all four rounds at Quail Hollow.

That issue appears to be behind him. The driver? He says he's figured it out — "I mean, come out and watch me hit balls, and you'll see," he said — which means the answer must have come during his weekend off after rounds of 71-78 at the Canadian Open last week left him far short of making the cut.

The 78 matched the second-worst score he's ever shot in a PGA Tour event.

The next test starts Thursday at a brutal, brutish Oakmont course that McIlroy said might be playing easier than the last time he was here. No, he wasn't talking about 2016, when he missed the first of three straight US Open cuts, but rather, last Monday, when he needed to go birdie-birdie down the finish to shoot 81 in a practice round.

"It didn't feel like I played that bad," McIlroy said. "It's much more benign right now than it was that Monday. They had the pins in dicey locations, and greens were running at 15 1/2 (compared to an estimated 14 1/2 for the tournament). It was nearly impossible. But yeah, this morning, it was a little softer."

Speaking of soft courses, McIlroy said he bristled at the reputation that began developing after his first major title, in 2011, when he demolished a rain-dampened Congressional with a US Open-record score of 268 that still stands.

His other majors — at Valhalla, Kiawah and Royal Liverpool — were also on soft courses. All that, plus his inability to capture the Masters, led critics to label him a player who couldn't conquer firm and fast.

"I didn't like that reputation because I felt like I was better than that reputation, so that's ego driven in some way," McIlroy said.

He tailored his game to handle the toughest conditions the majors can offer. He has runner-up finishes at the last two US Opens as proof that project worked.

But golf always presents new challenges. These days, McIlroy's is whether he can find that kind of fire — this week, next month, next year or beyond — now that he had made it over his biggest hump at the Masters.

He served up one clue of where his head is when asked what his plan for the next five years might be.

"I don't have one. I have no idea," he said. "I'm sort of just taking it tournament by tournament at this point."

Agencies via Xinhua