Signs for the 2018 Masters golf tournament at Augusta National. (Mike Segar/Reuters)

One of golf’s toughest tests gets underway Thursday with the start of the Masters. Augusta was the second-toughest course on the PGA Tour in 2017, with scores averaging 1.887 strokes over par.

But not all holes on the course are equal in difficulty. Some require would-be champions to record a low score, while on others escaping with a par is just as good as a birdie.

After analyzing how the course treated past Masters champs, it seems these three holes will decide who leaves in a green jacket in 2018.

No. 1: Tea Olive (Par-4, 445 yards)

The opening hole of the course, deemed the 13th-toughest hole on the PGA Tour by, played the toughest of any hole in the opening two rounds of last year’s event. Historically played 0.24 over par, Tea Olive begins with a dogleg right tee shot and then requires a pinpoint second shot to set up a makeable putt. Of course, with Augusta’s calling card being undulating greens, the putt will still likely be obscenely difficult.

As Rory McIlroy put it, “You don’t want to feel like you’re playing catch-up on this golf course.” Bogey the first and you will be.

Each of the last five Masters winners played it no worse than 0.25 over par, logging no worse than bogey. In fact, according to ESPN Stats and Information, the last 21 Masters champions have combined to produce just three double bogeys or worse. Data Golf also found that Tea Olive contributes about 5 percent to the variance in total scores at Augusta.

No. 11: White Dogwood (Par-4, 505 yards)

Welcome to Amen Corner, where wind has been known to sweep a player’s ball — and probability of winning — into the woods.

Last year, this hole played no easier than the second toughest in three of the four rounds, and it is historically played at 0.30 over par. The longest par-4 on the course yielded nearly six times more bogeys than birdies. No surprise, then, that dubbed it the second-toughest hole on tour.

“I believe it’s the hardest hole on the golf course,” Phil Mickelson said. “It’s certainly the toughest par on the course.”

With the tees having been moved back twice since 2002, the difficulties of this hole have manifested more over the last decade and a half. A downhill tee shot requires precision — particularly when wind is a factor. Then players must avoid the water to the left of the green.

Data Golf found that White Dogwood contributes about 5.7 percent of the variance in total scores, and in 2017, according to the PGA, golfers had an average score of 4.373 on this hole, the second-most over par after hole No. 1 with more than a third of the golfers in the field averaging a bogey or worse.

2017 Masters Par Yards Average score Average over/under Eagle Birdie Par Bogey Double bogey
No. 1 4 445 4.462 0.462 0% 6% 52% 34% 5%
No. 11 4 505 4.373 0.373 0% 5% 58% 33% 4%
No. 18 4 465 4.274 0.274 0% 13% 53% 28% 5%
No. 12 3 155 3.233 0.233 0% 8% 67% 20% 3%
No. 5 4 455 4.212 0.212 0% 7% 64% 27% 1%

No. 13: Azalea (Par-5, 510 yards)

Although Azalea played as the easiest or second-easiest hole at Augusta in all four rounds last season — and historically plays as the second easiest — it’s provided the most variance of any hole at Augusta over the last 35 years, according to research from Data Golf.

The 13th hole, Data Golf found, contributes about 8.4 percent to the variance in total scores, 1.3 percentage points more than any other hole, meaning it is the hole at which contenders separate themselves from the pack most. When Jordan Spieth went wire to wire in 2015, he birdied it four times, joining 13 other champions who were 4 under or better on the hole.

So while its difficulty isn’t necessarily in question — players produced 128 birdies and just 22 bogeys last year — the open par-5 is a scoring opportunity that can’t be wasted.

With two of the three most critical holes coming on the back nine, look for contenders such as Justin Thomas, Paul Casey and Dustin Johnson — all of whom rank in the top three in back-nine scoring average — to score in the red this weekend.