Rory McIlroy made a good start to life without long-time caddie JP Fitzgerald with an opening 67 in the WGC-Bridgestone Invitational in Akron.
McIlroy carded five birdies and two bogeys at Firestone Country Club to finish three under par alongside playing partner and Open champion Jordan Spieth, two shots behind clubhouse leader Thomas Pieters.
All four of McIlroy's major titles came alongside Fitzgerald, but the last of those was in 2014 and McIlroy admitted he was increasingly taking his frustrations out on his caddie.
Harry Diamond, the best man at McIlroy's wedding and a former top amateur player in his own right, has replaced Fitzgerald on the bag and although it remains to be seen if the relationship becomes permanent, McIlroy joked on Wednesday that "if we have a good fortnight, you never know".
"It was good," McIlroy said of a round marred somewhat by a three-putt bogey on the ninth, his final hole, following a poor approach.
"I'm taking a little bit more responsibility on myself and there were a couple of times where I probably should have hit another club, but that's on me, not anyone else.
"I'd much rather be frustrated at my own decision than someone else's. It's great to have my best mate on the bag and we're just having a good time.
"It was strange the first couple of holes. It's different but I stuck to it today, I played pretty well. I guess it's the start of the next chapter in my career and we'll go from here."
McIlroy admitted he was still struggling with his wedges but added on Sky Sports: "The putter feels really good.
"It felt good at the Open and I've been working hard on it, trying to blend the technical stuff with a little bit of feel as well and I feel like it's coming together.
"I didn't feel like I had my best stuff at Birkdale but I was able to finish decent. I really feel like I tuned a corner at Birkdale and it's nice to open with a good round here."
Pieters, who partnered McIlroy to three victories on his Ryder Cup debut, fired five birdies in a bogey-free 65 to lead by a shot from Scotland's Russell Knox, who missed out to Pieters for a wild card in 2016.
European captain Darren Clarke selected Lee Westwood, Martin Kaymer and Pieters to complete his team as Knox - the world number 20 at the time - was overlooked despite being ranked higher than all three.
Knox would have made the team automatically if he had been a European Tour member when he won the WGC-HSBC Champions in November 2015. He also won the Travelers Championship just three weeks before the wild cards were announced.
But after ending 2016 with three consecutive top-10 finishes, the 32-year-old has yet to record a single one this season and has missed the cut in 10 of his 18 events, including the last three in a row.
"I haven't really got off to many good starts of late so shooting four under round this tough track I'm very happy with," Knox, who has reverted to the putter used for his WGC victory, told Sky Sports.
"Wi nning a WGC for my first victory was a dream come true, I still pinch myself. They are massive events, right behind the majors because the fields are so strong. It's a great honour to be a WGC champion."