Willett, who in April became the first reigning champion to miss the cut at Augusta since Mike Weir in 2004, has withdrawn from three of his last seven events with a back injury that has severely hampered his performance.
The 29-year-old was 76th of the 77 players to make the cut in the Open Championship at Royal Birkdale and shot 21 over par in finishing last in the WGC-Bridgestone Invitational on Sunday.
That was the final straw and prompted an amicable split with long-time coach Pete Cowen, with Willett now working with Sean Foley, who coaches Justin Rose and used to work with Tiger Woods.
“It’s always tricky to take feelings that are completely different to what you’ve been doing for four or five years to a golf course, but we grinded it out quite nicely,” Willett said after an opening 73 at Quail Hollow.
“We hit a few bad ones, a few good ones. It’s a real work in progress. I’m really looking forward to a long-term goal and something we can work on over the next few months and try to get back to somewhere near where we can be.
“I’ve been working really hard and done everything that has been asked and I just wasn’t really seeing results.
“It’s not that you’ve chucked the toys out of the pram and been swearing at everyone, it was very amicable.
“I want a different set of eyes looking at it, a bit of a fresh start to try and get really excited about working on some different stuff.
“Foles came up with a few nice things this week. Between me, Mike (Walker) and Pete it’s easy to miss things and slip into patterns of doing the same things knowing that it’s worked in the past.
“I’ve known Foles for a while now and really like him as a character first and foremost and that then helps you jump in fully with both feet and trust what someone’s saying.
“He’s very scientific with his approach so I’m looking forward to seeing what the next two or three months brings.
“I live 10 minutes from Mike and Pete’s range so I’m sure I’m still going to go up there and have plenty of cups of tea with Pete and keep in touch.”
A late rally ensured Jordan Spieth kept his bid to become the youngest player to complete a career grand slam on track in the 99th Championship.
Spieth’s dramatic Open victory at Royal Birkdale means another at Quail Hollow would see him join Gene Sarazen, Ben Hogan, Gary Player, Jack Nicklaus and Tiger Woods in having won all four majors.
But the 24-year-old had to recover from three over par with three holes to play to card a one-over-par 72 and lie five shots off the lead held by Denmark’s Thorbjorn Olesen.
US Open champion Brooks Koepka was a shot off the lead along with fellow Americans Grayson Murray and Gary Woodland, with England’s Paul Casey another shot back on two under.
Koepka said he “felt like c**p” after hitting a marshal on the head with an errant drive.
Koepka’s tee shot on the 16th – his seventh hole of the day – was flying towards spectators to the right of the fairway when it hit a marshal who was standing just inside the ropes.
The man was knocked to the ground and was pictured bleeding from a head wound, although he was able to joke with Koepka that he had done him a favour by diverting the ball back onto the fairway.
“I felt terrible about it,” Koepka said, although he had not shouted the traditional warning of ‘fore’ following his drive.
“He was laughing and joking when I was up there, kept telling me, ‘You got a good break’. I was like, ‘well, I still feel like c**p’. But I got his information so I’ll probably reach out to him and see how he’s doing.
“I’m sure he’s going to have quite a big headache.”
Tommy Fleetwood was delighted to overcome “brutal” conditions in the first round and remain in the spotlight for a third straight major championship.
After finishing fourth in the US Open, Fleetwood was one of the favourites for the Open Championship at Royal Birkdale.
“I didn’t really feel pressure at Birkdale, I just thought it was a new experience, being talked about as a potential winner of a major,” Fleetwood said after carding three birdies and two bogeys in an opening 70 yesterday.
“I’m very happy. The course is brutal, really. It’s a really tough test. Anything par or beating the course is a great score.”
Casey shot a two-under-par 69, but fellow Englishman Andrew Johnston was forced to withdraw from the tournament with a shoulder injury.