MANILA -- Amateur Mafy Singson made a huge 10-stroke turnaround to jump from the middle of the pack to the top of the leaderboard in the ICTSI Valley Golf Challenge in Antipolo on Wednesday.

After a seven-over 79 showing in the first round on Tuesday, Singson came alive to tally a three-under 69 in the second round to drive past Chihiro Ikeda and Korean amateur Min Yeong Kim.

Singson, who is in search of her second pro crown, found herself ahead of the pack as Ikeda and Kim made two bogeys each at the finish, holing out with 75 and 73, respectively, and dropping to a three-way tie instead with Daniella Uy at 149.

Just a stroke off Ikeda after 18 holes, Uy took charge with a two-birdie, two-bogey card after 11 holes but made two more bogeys in the next five and wound up with a 74. Still, her effort kept her within a stroke off the new leader with 18 holes left in the P750,000 championship.

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"My driving wasn't so good (in the first round). In this course, you really need to drive well to be in the fairway all the time. I drove a lot better today (yesterday) but still not good although I was able to save more (pars) and made more putts," said Singson, who upstaged the top pros to snatch the LPGT Splendido Taal crown last year.

She underperformed in previous legs of the ICTSI-backed cricut before her blistering second round put her in contention in the Antipolo course.

"I'm excited. But I'm hoping for the best tomorrow (today). I hope to play steady and well," added the ICTSI-backed shotmaker.

Ikeda fell off the leaderboard with an error-riddled start in hot conditions but as her rivals also tumbled one after the other while facing severe tests at Valley South in dark skies early in the afternoon, the reigning Ladies Philippine Golf Tour Order of Merit champion birdied the 11th to regain control.

She bogeyed No. 14 for the second straight time but came up with a chip-in birdie from 40 yards on the next, only to come up cold at resumption of play.

"I had no problem with the delay. In fact, I was able to relax since I was already tired. But the course is really tough," said Ikeda.

Rookie pro Mikha Fortuna, meanwhile, also moved into strong contention with a 71 for a 150, just a couple of shots off Singson at fifth, while Martina Miñoza also remained in chase despite a 76 for a 151 and three-peat seeking Harmie Constantino and amateur Lois Kaye Go matched 152s after a 76 and 74, respectively, to guarantee a wide-open finish.