The 29-year-old American, seeking his first professional victory, had what he called a “stress-free” round sprinkled with eight birdies.
“I got off to a good start by making some good swings and had a 10-foot look at eagle on three which kind of got my round started,” Barnes said.
Ryan Moore (64) trails by one stroke, while Canadian Open winner Carl Pettersson (65) was two back along with Brian Davis and Charlie Wi.
Moore, who arrived in Malaysia on Friday to acclimatize to the time change and humid weather, had seven birdies. He has earned more than $2 million this season on the PGA Tour but has no victories.
“For me, this is my last chance to get a win and finish off the year the way I want to,” the American said. “It was a good season. I feel like it was better than last year, and last year I had a win. That’s what I’m coming here for. It’s my last tournament of the year.”
The 40-man tournament at The Mines Resort and Golf Club, which has Ernie Els (67), Luke Donald (67) and Retief Goosen (69) in the field, is also sanctioned by the Asian Tour. The winner will receive $1 million from the $6 million purse.