Any list of the PGA Tour’s most popular players has to include Jordan Spieth, and anyone who has followed the Texan closely for his Hall of Fame career will also recognize his caddie, Michael Greller.

Spieth is a three-time major winner who is one of the sport’s most popular players, largely due to his playing style. The former Texas Longhorn has a habit of spraying the ball all over the place only to make sensational recovery shots.

That volatile playing style means he needs a lot of advice (and therapy) on the course, and the 48-year-old Greller has served those roles for his boss’ entire career.

Here are five fast facts about Jordan Spieth’s caddie, Michael Greller.

1. Greller Was a Math Teacher In His Previous Life

Before entering the world of professional golf as a PGA Tour caddie, Greller was a middle school match teacher in Washington. He was making $55,000 a year at the time.

“I was never looking to get out. It was an incredibly rewarding career,’ Greller told ESPN in 2017.

It turned out pretty well for Greller, who has made at least an estimated $7 million over his career. He also credits teaching for helping on the course.

You have to think on your feet, adapt to stress, have patience, be an encourager and have a servant’s heart,” he told his alma mater, George Fox University, in 2014. “In other words, teaching did a lot to prepare me.”

2. Working for Justin Thomas led to Spieth

Thomas and Spieth are close friends, as are Greller and Thomas. The two worked together in 2010, when Thomas had Greller on the bag at the 2010 U.S. Amateur at Chambers Bay. Thomas is credited for helping to get Greller and Spieth linked up, and Greller started working with Spieth a year later.

“I obviously would have liked for him to caddie for me at the start because he is a great buddy of mine and I always thought he was a great caddie,” Thomas said in 2015. It’s just the way it worked out and I think he is a really, really good fit for Jordan, the way they mesh.”

3. Greller’s Wedding Had Golf, Career Connection

Greller and his wife, Ellie (also a former teacher), got married in 2013 at Chambers Bay — where he caddied for Thomas in 2011 and where Spieth won the 2015 U.S. Open. Chambers Bay is also where Greller spent summers as a caddie while working as a teacher.

4. Greller Has a Great Augusta National Story

There are very few golfers in this generation who have as much recent history at the Masters as Spieth. Greller has had a front-row seat to all of that history — good and bad.

But his first trip to Augusta National Golf Club came the old-fashioned way: He had to win the ticket lottery. Greller revealed to Golf.com’s Claire Rogers that he won tickets to a Tuesday practice round in 2012 via the lottery.

Little did he know at the time he’d be on the bag for Spieth’s Masters debut two years later where the then-20-year-old was tied for the lead entering Sunday before Bubba Watson ultimately prevailed. Of course, Greller was also there again a year later when his boss slipped on the green jacket (as well as the historic collapse in 2016).

5. Spieth, Greller Have One of Golf’s Funniest Relationships

Just like Spieth’s golf game, his relationship with Greller doesn’t always look pretty, but it works. When the two are mic’d-up, or a microphone is nearby, it leads to sensational content.