AKRON, Ohio — With a new caddie on his bag, Rory McIlroy looked like the Rory of old in Thursday’s first round of the World Golf Championships-Bridgestone Invitational.

Despite a last-hole bogey the result of a three-putt from 51 feet, McIlroy looked like his old powerful self and was at ease throughout his tour around the South Course at Firestone Country Club. The former world No. 1, who is winless this year, signed for a 3-under-par 67 and stood two strokes behind pace-setting Thomas Pieters.

“Overall it would have been nice to finish 4 under,” the four-time major winner said. “I think 67, with how I hit it and some of the up‑and‑downs I made, I think it was a fair reflection of how I played, so I’m happy enough with how today went.”

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In step with McIlroy was his best mate from childhood and his best man at his wedding, Harry Diamond. McIlroy split with long-time caddie J.P. Fitzgerald two days after finishing in a tie for fourth in the British Open and called on Diamond this week and next week at the PGA Championship.

McIlroy said he wanted to take more ownership of his game and needed to make a change.

“It was good. A little weird at the start. Obviously it’s been nine years since I’ve had anyone else on my bag, so even just hearing a different voice, it’s a little different,” McIlroy said. “But I thought we did well out there, sort of consulted each other when we needed to. I sort of did all my own stuff when I felt like I was good and then whatever decisions I made, whether they were good or bad, it was on me. Didn’t have anyone to get frustrated at other than myself. …

“There were a couple of shots that I hit or a couple of clubs that I pulled that I maybe should have just thought a little bit more about. It’s been a while since I’ve paced yardages off and written notes in my book and all that sort of stuff. It was good.”

McIlroy, bothered all year by a rib injury, is playing in just his 12th tournament of the year. His driver, long considered his best weapon, was in sync as he averaged 330.6 yards off the tee. For the most part, his iron play was solid. His putting, on…