The 2017 FedEx Cup victor and two-time defending champion in Malaysia began his 2017-'18 PGA Tour season with a good-but-not-great two-under 70 at TPC Kuala Lumpur, his second-worst round in the event. He also shot 62 at this event past year.
The $7 million CIMB Classic is co-sponsored by the Asian Tour and PGA Tour, with prize money for the victor of $1.26 million.
Matsuyama, 25, has been on good form with six titles around the world, including two World Golf Championships tournaments, over the past year. He successfully defended it a year ago, and has had a transformative 2017 in which he's won five titles and his first major, the U.S. Open.
If Justin Thomas is going to win his third straight CIMB Classic, he's got some work to do. The last player to win his first start in a tour event was Jim Benepe at the 1988 Western Open. "I hope that this momentum will last until the end", she said. "I tried to copy everything [Justin] did as I figured he's a good guy to imitate out here".
Smith, who won his first US PGA Tour title at the Zurich Classic team event in May, picked up five shots on the way out and three more over the last five holes to stand a shot clear of Thai Poom Saksansin and Americans Xander Schauffele and Keegan Bradley.
Australian Cameron Smith, ranked number 151 in the world, took the lead with a sparkling eight-under-par 64.
"It was pretty simple really, hit a lot of good shots today and made a lot of good putts", he said.
Three players are tied for fifth with 66s: Kevin Na, Gary Woodland and Pat Perez.
World number three Matsuyama will likely be the 24-year-old's main rival again at the event this year, and could push him to the limit in the sweltering tropical conditions.