SANDWICH, England -- There is no mistaking the bunkers here, no disputing what constitutes a hazard at Royal St. George's. They are deep and treacherous and penalizing without the indignity of grounding your club in one of them.
That fate, of course, befell Dustin Johnson last summer at Whistling Straits, a course that looks like a links but has bunkers that look like dirt.
That led to some problems for Johnson, who missed a playoff due to a penalty when he didn't recognize a bunker. It helps that they are so defined here. It also helps to have an experienced caddie who has been around these parts.
Lugging the bag for Johnson these days is Joe LaCava, the longtime caddie for Fred Couples who took on the duties for America's rising star earlier this year.
He was on the bag for Couples when he tied for ninth here in 1993 and again when he was 46th in 2003 as well as about a dozen other Opens and Couples' Masters victory in 1992.
"That just shows how old I am," LaCava said.
LaCava downplays what benefit he brings to Johnson as he heads into the final round at the Open Championship in the final group with Darren Clarke. But his steadying presence and experience certainly can be of value.
"Obviously it's good to have a guy that's got a lot of experience," Johnson said of LaCava. "I mean, first of all, we get along very well, and I think a key to having a good caddie is getting along well and then also trusting him, and I trust him. We've done very well so far, and hopefully we can do a little better."
Johnson didn't handle the on-course situations very well last year when he held a three-stroke lead heading into the final round of the U.S. Open, and then he had a chance to win the PGA Championship at Whistling Straits.
He shot 82 at Pebble and had the bunker fiasco at the PGA. Although he did win later in the year at the BMW Championship -- his fourth PGA Tour title -- Johnson has been relatively quiet this year. He has four top-10s and was in the final group at Doral, where Nick Watney beat him.
"Obviously I've been in this situation a few times, so I think the more and more you can put yourself in a situation, the more comfortable you get," said Johnson, 27. "I'm going to be pretty comfortable out there tomorrow because I know what to expect, I know how to approach it, and I know what I do in those situations.
"So I do understand it, so hopefully I can go out tomorrow and play some solid golf like I've been doing the last few days."
This is just the third Open Championship for Johnson, who missed the cut two years ago at Turnberry and then was 14th last year at St. Andrews. Prior to that, his only links experience came in a college event played down the road from St. Andrews when he played at Coastal Carolina.
Nonetheless, LaCava doesn't find himself holding Johnson's hand around the links.
"He knows what's going on," LaCava said. "He likes to hit different shots. He can [hit] the little bump and run. Doesn't have a ton of experience. But he has 'it,' so to speak. Like Fred had 'it' too. I see the same in this kid."
Johnson would never even be in this position -- might not have even made the cut -- had he not rebounded nicely from a horrible start to the tournament.
He was 4 over through 10 holes Thursday, then made three birdies and an ace on the back nine and finished at par. "That was huge," LaCava said.
Despite making 10 bogeys for the week, Johnson has offset that with 12 birdies and an eagle to get to 4 under and trail Clarke by one.
This will be the third time in five majors that he's played in the final group, having coughed up the lead to Graeme McDowell at the U.S. Open, then trailed Watney by three at the PGA Championship, where he was a stroke ahead of Martin Kaymer and Bubba Watson on the final hole.
The short version of the story: He hit his tee shot way right into what appeared to him to be a dusty, dirt pan lie. Neither he nor then-caddie Bobby Brown sought out a rules official to ask if the area was defined as a bunker. And neither had read the rules sheet stating that all waste areas were to be treated as hazards.
That meant when Johnson placed his club behind the ball, he touched the sand, incurring a two-shot penalty -- none of which he knew until after he two-putted for a bogey that he thought put him in a playoff.
Instead, he had to suffer the indignity of blowing his chance because of a highly controversial bunker.
Johnson faced a different kind of adversity Saturday. He's been ill for most of the week, suffering from a bad cold that couldn't have been made better by the horrendous conditions much of the field faced during the third round.
"It was as bad as I've seen," said LaCava. "This is a tough day for everybody, but for caddies, you need 10 hands to do everything."
And yet, when Johnson's round was coming to an end, the sun had come out. He had to deal with the brutal conditions for only the first five or six holes. That allowed Johnson to match Rickie Fowler with the day's low score, a 68.
He was aided by LaCava, who knew to calm Johnson on the 18th tee after he made a bogey at 17, having short-sided himself in a bunker. Johnson was understandably upset, but LaCava got him back to the work at hand.
"Last year was a learning curve," LaCava said, repeating the mantra of the boss, who has often said his experiences at Pebble Beach and Whistling Straits would be of benefit down the road.
"Given the way he's played the first three days, I don't think you can go against that," said Phil Mickelson, who is five strokes back of Clarke and played a practice round with Johnson this week.
"Plus the fact that he's been there before and he knows what hasn't worked for him, and then he also knows what has worked for him in some tournaments. And I think he'll be more ready than ever to play."
Will he? That's what we will find out Sunday.
Bob Harig covers golf for ESPN.com. He can be reached at BobHarig@gmail.com.