The Colombian bogeyed his first hole but bounced back with three straight birdies and two hole-out eagles en route to the lowest score of Day 1. Munoz placed ninth at last week's CJ Cup and has three top-10 finishes in his previous six PGA Tour starts.
After posting even on the front nine, Thomas finished his day by going eagle-birdie-birdie to sit one off the early pace.
Hatton, who led after 18 holes at last week's event in Las Vegas, continued his recent run of incredible form with a one-bogey 65.
Here's how the leaderboard stands following Day 1:
|Place||Player||To Par||R1 Score|