Scottie Scheffler one back of good friend Si Woo Kim at The American Express

The South Korean carded a six under 66 around La Quinta Country Club, enough to take him to 22 under for the tournament. Scheffler and 18-year-old Blades Brown each carded 68s, leaving them one shot behind Kim.

Kim actually carded his first bogey ofthe week on the par three third, but otherwise lit up the front nine with four birdies, then had three more coming home.

Scheffler and Kim go way back. The American helped Kim get a membership at Royal Oaks in Dallas, and they are regulars at the weekend game. They competed plenty in the month leading up to The American Express.  

"Have you ever spent any time with him? He's hilarious," said Scheffler of his friend.

Meanwhile, the story of the day is teenager Brown. His three straight birdie finish saw him tie with world number one Scheffler. But his form comes off the back of playing four round of the Koren Ferry Tour earlier in the week. Not that he's tired.

"I feel great," said Brown.

"I got another opportunity to see what we can make happen tomorrow. Got another 18 holes and, yeah, should be fun."

Should Brown win, he would be the youngest PGA Tour champion in over 100 years.