Who is Jordan Spieth's caddie?

US golfer Jordan Spieth is easily one of the most prolific players in the game right now. He is a three-time major tournament champion and has also won the 2015 US Open. Spieth won the 2015 Masters by tying Tiger Woods' 1997 record of 72-holes. The 29-year-old has had a meteoric rise ever since turning professional in 2012.

And his long-time caddie Michael Greller was with him on this journey every step of the way after the two joined forces in 2011. Greller continues to be his caddie as the young golfer takes on more championships.

The dynamic between Jordan Spieth and Michael Greller is entertaining to say the least. Their equation is often described as an old married couple who are constantly bickering. This description seems about right, if their amusing tiffs on the greens are anything to go by.

During the third round of the BMW Championships in August this year, Greller and Spieth had an on-field debate about attempting a risky shot. Jordan Spieth had a share of the lead, heading into the par-4 No. 5. However, the ball was left in a fairway bunker due to a wayward shot.

The water defended the green and Spieth was left with only two choices—bail out and play a safe swing, or go for broke out of the bunker.

It is in situations like these, where golfers usually turn to their caddies for an opinion. From the sand, Spieth told Greller:

"I mean, this is the same as where I was in yesterday. So if I strike it well, if it's up, it's on the green."

To which Greller replied:

"Yeah, I know. What's wrong with hitting right here, having a wedge to 15 feet?"

Despite Greller's constant advice for Spieth not to attempt such a risky shot mid-tournament, Spieth was insistent. So, he set up a shot, took a swing, and it only took him a moment to realize his folly.

The ball fell right into the middle of the water and Spieth double-bogeyed the hole. While this gamble didn't pay off as Spieth had hoped it would, it is important to note that most times that Spieth has gone with his gut, he has been successful.

Jordan Spieth is known for having an overflowing nervous energy on the field and Michael Greller is his voice of reason. When Spieth is overwhelmed with a million thoughts at the same time, he turns to Greller, who maintains perspective, reins in the golfer's wildest instincts, and keeps his mind on track.

In fact, Spieth revealed last year that the duo shared a "safe word" to keep the golfer from spiraling. So the two have found a way to prevent Spieth from being overwhelmed with negativity and potentially derailing a round because of it. He spoke about it albeit without revealing what the safe word was during the podcast, No Laying Up.

"We've kind of developed this system where if it feels like I've just been over-talking, he's got a kind of safe word where he just says something, and then I can't talk anymore until the next shot. It's only when I've gone really overboard, and he knows what it is. It's only when I'm just repeating myself, going in a circle."

So, despite the entertaining debates that have been caught on broadcast, one thing that has to be highlighted is the great partnership and unconditional trust that the two share.

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Michael Greller was a math teacher before caddying full-time for Jordan Spieth

Jordan Spieth and Michael Greller (Image via Getty Images/Warren Little)

Michael Greller's story does somewhat seem like a film script. Before caddying for Jordan Spieth for the biggest golf championships and lifting the trophies, Greller was a high school math teacher living and working in Seattle.

He would work as a caddie in his local area for some extra money when he met Jordan Spieth, who was an amateur golfer at the time. The two teamed up for the US Junior Amateur that happened in Greller's hometown in 2011. The following year, Spieth became the world's leading amateur golfer and joined forces with Greller again for the 2012 US Open.

After turning professional, Jordan Spieth asked Michael Greller to caddy for him. Initially, Greller intended to take away just one year from his day job but soon realized how fast Spieth was growing through the ranks.

Halfway through his debut season, Spieth won the John Deere Classic, becoming the first teenager to win on the PGA Tour since Ralph Guldahl in 1931. 2015 was the greatest year for Jordan Spieth professionally. In fact, he had the best year amongst all golfers.

He bagged the Masters and the US Open. The latter took place at Chambers Bay, which Greller knew very well as he got married there. Well, the rest is history.

Part of the golfer's earnings go to the caddy, so Michael Greller has surely earned a fortune, especially in 2015. He has developed a net worth of around $10 million.

Pairing up was a risky decision for both Jordan Spieth and Michael Greller. For Spieth, because he was partnering with a caddy who did not have the experience of big leagues, and Greller left a stable teaching job to caddy for Spieth.

But the risk paid off. And the two stuck together, in Spieth's own words, through the "highest highs and some of the lowest lows."