US Open: Dustin Johnson and Brooks Koepka's trainer on how he helps major winners
There will be big hitters and booming drives aplenty at Pebble Beach when the US Open begins on Thursday.
Professional golfers are now finely tuned athletes, stronger and fitter than their predecessors with many boasting the physical prowess to rival counterparts from traditionally more athletic sports.
Sitting top of the class are Brooks Koepka and Dustin Johnson, who finished first and second at last month's US PGA Championship and are currently ranked as the best two golfers in the world.
So what is their secret?
Both work with Joey Diovisalvi, one of the pioneers in golf-specific fitness training and a biomechanics expert, who welcomes some of the top men's and women's players to his academy in Florida.
More than two decades ago, Diovisalvi recognised the need for players to evolve physically and set about putting the science behind the perfect swing into practice.
"It intrigued me because golfers were not so keen on the physical aspects - they were slow, late adapters and it took me a long time to create some acceptance and trust in that world," Diovisalvi, who credits 15-time major champion Tiger Woods as an early influencer in the field, told BBC Sport.
"I look at golfers today like Dustin and Brooks - an Adam Scott, a Jason Day and a Rory McIlroy - players of this calibre, they're very athletic, the human body has evolved, the science has evolved, the equipment has evolved.
"You look at them and the average player out on tour, their bodies have changed in height, weight, physicality... you see this huge shift in the game. Physicality can overpower a golf course.
"You have to be such an amazing player to be able to compete with the guys at the top of the game."
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Diovisalvi uses the example of England's Tommy Fleetwood, who finished runner-up at the US Open last year and is ranked 18th in the world despite his relatively smaller stature.
"I love Tommy and his trainer because he is like a Samson and Goliath," he said. "I see the way Tommy trains. He's in the gym so many times at the same time Brooks and I or Dustin and I.
"Tommy is relentless in his pursuit of his strength, conditioning, mobility, flexibility. He and his trainer do such a phenomenal job and Tommy has really been able to compete with the bigger guys, but if his game is off it's very hard to put the ball in a position to score when they are out-driving you by 50/60 yards."
A day in the life of DJ...
Diovisalvi headed to the Canadian Open with world number two Johnson last week as the American put the final touches on his preparation for the third major of the year.
"Dustin is in a good place," he said. "He's hitting it well and he's more comfortable with the putter. His body has been slowly and gradually building up to this major. He loves Pebble Beach, so I am very confident in the way he's approaching this week and used Canada as an opportunity.
"Mentally it preps these guys to have enough reps to feel good about where their driver is, where their short game is, the approach shots - what does it look like with the irons?
"It's a really good test to see how the body and the swing are working. Dustin's body is peaking nicely."
Helping players get their "feel" is a key part of Diovisalvi's role.
"As the coach and the player are trying to get something to feel right, especially before a major, our job is to make sure the body and the nervous system understand how to ingrain that without over-thinking," he added.
"When their feel is off, you see them do things that are out of character for the calibre they play at. You hear the commentators, they start to over analyse and that's not really what it is... the reality is, if the feel is right and their bodies are reacting and they feel good with where their mental game is, it's a pretty seamless effort.
"Then it comes down to can they putt well to score?"
But life on the PGA Tour can be intense, with players enduring long, hectic days that run far beyond what is picked up by the cameras during their rounds.
"It's not just a sunshiny day and they show up on the tee box or the driving range and go and play a five-hour round in the sunny weather," explained Diovisalvi, who has previously worked with three-time major winner Vijay Singh.
"Both Brooks and Dustin take their nutrition very seriously, they had chefs with them this week and rented homes so they got more of a feel what it's like to have their support team around them, their family, the opportunity to sleep better, to eat better."
|A day in the life on tour, eg 07:00 tee time|
|04:00: Wake Up|
|04:40: Eat breakfast|
|05:00: Arrive at golf course-10 mins on stationary bike-10 mins full dynamic stretch-15 mins stability/mobility/functional exercises|
|05:45-06:55: Practice range|
|07:00-12:00: Play round|
|12:00-14:00: Interviews, lunch, practice (if necessary), rest|
|16:00-17:30: Full 90-minute gym workout|
After an early wake up - 04:00 if on the first tee at 07:00 - the players warm-up in the fitness trailers provided by the PGA Tour that are kitted out with the latest technology.
"Dustin will get on a spin bike for 10 or 12 minutes, get blood flowing, get his heart rate going a little bit," added Diovisalvi. "Then we get down on a mat and do a very active, dynamic stretch for another 10 minutes."
Next, the 2016 US Open champion works through a number of drills using stability balls, dumbbells, resistance bands and medicine balls to engage the muscles used during his round.
"He's using very dynamic movement patterns that mimic the golf swing," said Diovisalvi. "He's very prepared in about 30 minutes to go out to the driving range and begin his routine.
"Now his feel or his body is very switched on. The nerves are firing, he feels the pressure from his feet.
"In 2019 we have worked harder than ever before on 'prehabilitation' - getting the body ready to perform so there's few chances of injury, higher performance levels, more ability to get the body to move properly."
Diovisalvi takes huge pride in seeing the players he and his team have worked with win tournaments and the academy in Jupiter, Florida is decorated with banners won by the likes of Johnson, Koepka, Justin Thomas, Lexi Thompson and Michelle Wie.
"They always say the proof is in the championship rings, or the banners that hang on our walls," he said. "The majors that have been won in our team, they humble me every day.
"You hang these banners and think 'gosh, we've been on teams that have helped win so many majors', it really is humbling what you have participated in and how you helped grow the game."