Singaporean golfer Mardan Mamat produced a masterful two-under-par 70 in tough conditions to open up a three-shot halfway lead after the second round of the $US300,000 ($A280,000) Philippine Open on Friday.

Chasing a third Asian Tour victory the veteran notched a two-day total of five under-par 139 with two birdies against no bogeys to lead American Ben Fox and local hopes Antonio Lascuna and Ferdinand Aunzo.

Paul Donahoo and Adam Blyth are both one-under for the tournament to be the best-placed Australians.

Lascuna battled to a 71, Aunzo shot a 70 while Fox scrambled to a 73 in Asia’s oldest national championship to lie on 142.

Coming off a low-key season in 2011, Mamat, whose last Asian tour victory was in 2006, broke away from a packed leaderboard with easy birdies on the fifth and 10th holes.

“Going into the last three holes, I told myself that it would be a bonus if I could stay bogey free and I managed to do it. The winds were more, it’s swirling a lot. I was pretty much in control of my swing,” said Mamat.

The 44-year-old finished 57th on the Asian Tour’s Order of Merit last season, his lowest position since 1998, despite enjoying one runner-up finish.

The 41-year-old Lascuna has won multiple titles on his domestic tour but is still dreaming of the big one on the Asian Tour, and a win on Sunday in his home Open would be particularly special.

After three birdies against two bogeys in his morning round he was happy with his performance so far.

“I think I have a chance. I’ll just enjoy the game. It’s exciting… I need a couple of two under par rounds over the weekend.”