More than two decades after his first victory at Saujana Golf & Country Club, Lee Westwood stormed into contention for his second with a brilliant 62 in the Maybank Championship.
The former world No. 1 won the Malaysian Open at Saujana in 1997 but has not tasted victory since 2015 and is currently not exempt for the Masters, an event where he finished second in 2010 and 2016.
"It was enjoyable, there were a lot of birdies going in out there," the 44-year-old said. "It's nice to be in contention and to know this golf course well. I was touring pro for this course, so I've probably played it more than most and I know where to hit it.
"I hit it close a lot and it was a pretty pain-free round. Gave myself a lot of birdie chances, so it was a really good ball-striking round and I holed out well as well. I was pleased with the way today went and hopefully we can build on that more.
"I played alright the first three weeks of the year. I missed the first two cuts but I sort of got in my own way mentally, not sure the reason for that but today I just freewheeled really and had fun out there."
Bertasio and 18-year-old Thai prospect Khongwatmai both shot 65 to set the pace on 11 under, with Westwood joined on 10 under by first-round leader Chris Paisley, Yuta Ikeda and Scotland's Marc Warren.
Warren was among the players forced to finish their first rounds on Friday after Thursday's weather delay and completed a 68 before adding a second round of 66.
"I'm really pleased overall," Warren said. "On this golf course if you only have one bogey [in two days] your game is going to be pretty solid and I feel every aspect is pretty good, so looking forward to the weekend."
The halfway cut fell at four under par and means the remaining 81-strong field is separated by just seven shots, with 50 players within five of the lead.