Xander Schauffele has transformed himself into a major championship killer

For years, Xander Schauffele was widely considered the best golfer in the world who didn't possess the killer mentality to win the big one. After firing a bogey-free 65 in the final round of the British Open to win his second major championship of the year, the American has officially shown that narrative the door.

Schauffele entered the final round at Royal Troon Golf Club one stroke back of leader Billy Horschel. It took him six holes to record his first birdie of the day on the gettable front 9, and he entered the brutally tough back 9 two shots back of the lead.

This was the point in Schauffele's past when he would press too hard and let the pressure affect his game. Coming up short on the back 9 was a theme during his 0-for-27 start to his major championship career.

But this time — with the invaluable experience of winning a major now in his back pocket — Schauffele went into killer mode.

After a near-birdie at the 10th hole, Schauffele stuck his approach to three feet on the intimidating par-4 11th and sank the birdie look. He was the only man to birdie 11 all day. He followed it up with back-to-back birdies on 13 and 14 to seize the outright lead.

On the par-5 16th, when he could've played it safe to hold his lead, Schauffele pulled his 3-wood from 298 yards out and blasted his second shot just short of the green. A nifty up and down over a pot bunker gave him full control of the tournament.

Schauffele recorded stress-free pars on 17 and 18 to close out a 6-under 65, the lowest score from any player in the final round. In Round 4, the menacing back 9 played to an average score of 2-over par with the wind blowing into the players' faces. Schauffele shot a 4-under 31 and barely broke a sweat doing it.

We're witnessing a stunning transformation from a player who struggled for so long to calm his nerves while in contention at a major championship. Schauffele looked as calm on Sunday as a weekend warrior playing his weekly round with his buddies.

Schauffele's refinement in majors is reminiscent of a basketball player searching for his shot. Sometimes all you need is to see one go in to kickstart a run, and Schauffele's run is just beginning.