Starting the round with a shaky one-point edge, Roberto made a couple of 27s under the Molave system for that 54, even-par in medal play, as the Southwoods bet pooled a 36-hole aggregate of 109, counting her first round score of 55.
That was six points up on Yao, who failed to sustain her solid 54 in the first day and faltered with 49 points on rounds of 23-26. She remained in second with 103 with one round left in the 54-hole tournament.
With Carmellete Villaroman and Jocel Pagunsan both tumbling down with 48 and 47 points, respectively, after a pair of 52s, Leanna Farrales of Wack Wack made her move by churning out 53 points to catch Southwoods Tracy Locsin, shooting 51 points, at third with 101.
Barring any disaster and another major foldup like she did in the RP Ladies Open last January, Roberto hopes to nail the crown unopposed in this event conducted by the National Golf Association of the Philippines.
Like Roberto, Mencie Millonado remained on top in Class A with 82 points after a 38 but the Wack Wack standout saw her overnight four-point lead reduced to just one as Negros Jocelyn Garcia, Sheila Dolosa of Bacolod and Hilda Badong of Riviera shot identical 41s to close in with 81 points.
Beth Menchavez, another bet from Riviera, bounced back from a mediocre 36 with 40 points although she remained six points off the pace with 76.
In Class B, Maribel Kawsek of Wack Wack seized control with a 72 after a 38 for a one-point lead over teammate Eloisa Campos, who had a 71 after a 37 in this event sponsored by DHL Worldwide Express, WWW Express, Petron Corp. Philippine Sports Commission, Gopez Corp., Sugarland Hotel, Directories Philippines Corp., Hans Brumann Jeweller, Casino Filipino Hotel, Mitsubishi Motors, Vice Admiral Luisito Fernandez, BREDCO, Nestle Waters Phils. Inc. and Mizuno.