Rory McIlroy revealed how much work he has to do before bidding to regain his Open title after an erratic opening round in the 100th French Open in Paris.
McIlroy was two under par after six holes at Le Golf National but eventually had to settle for a level-par 71 featuring four birdies, four bogeys and two trips to the water at the 2018 Ryder Cup venue.
That left the 27-year-old five shots off the lead held by Denmark's Lucas Bjerregaard, whose 66 gave him a one-shot lead over defending champion Bernd Wiesberger, Belgium's Thomas Pieters, Thailand's Thongchai Jaidee and Spain's Adrian Otaegui.
McIlroy has been putting in the hours on the range with coach Michael Bannon ever since an opening 77 in the US Open led to a first missed cut in a major championship since the 2013 Open.
And asked what areas he was working on, the four-time major winner joked: "Have you got 10 minutes?
"My left-hand grip is too strong. Takeaway was going on the inside. Wasn't holding my right elbow properly at the top of my swing. Wasn't getting my right knee out of the way on the downswing... I've been working on a few things.
"I was joking with my friends at the weekend; I've got 17 swing thoughts down to about five, so I'm doing okay. Try to get that to two next week.
"I've got another hopefully three competitive rounds here. I've got all next week and then obviously a few days leading up to the Thursday of The Open. So hopefully by then, it will be all bedded in."
McIlroy, who was unable to defend his Open title in 2015 after suffering an ankle injury during a game of football with friends, added: "I think the hardest thing is that I haven't focused on my grip since I changed it when I was maybe 12 years old. Progressively the left hand got a bit stronger and stronger and that clubface is coming in closed at impact.
"Gripping the club feels quite strange at the minute but I just need to stay with it. Bigger picture, it's the right thing to do. They are not major changes. They are tweaks trying to get it back to where I know I can be.
"Every tournament is important and you want to try and play well but sometimes it just has to be done."
Despite his problems, McIlroy still fared better than Masters champion Danny Willett, who double-bogeyed the 18th after finding water with his approach to card a 75 and face the prospect of a second consecutive missed cut.
Playing partner Lee Westwood, who finished second to Willett at Augusta, was only a shot better off, while two-time winner Graeme McDowell slumped to a nine-over-par 80.
Bjerregaard's 66 contained a hole-in-one on the second hole from 202 yards and five birdies, despite playing with a new set of clubs after his own had been lost in transit.
"It was a great way to start my round," the 24-year-old said. "It's my first ever hole-in-one, so that was pretty sweet. It was a perfect number for a seven iron downwind. I hit a great shot straight at it but we couldn't really see it.
"It looked like it went in, but about five guys were at the back of the green and nobody clapped or reacted in any way and then Matteo (Manassero) said he thought he could see it right behind the pin. I grabbed my putter and we started walking and when we got a little closer we could see no ball on the green.
"My clubs got lost on the way down here so Nike made me a new set yesterday. Maybe I should just keep these now and let the airline company keep my old ones."