Lagman, a bet of Central Visayas to the Palarong Pambansa, silenced Kaye Repunte, 6-0, 6-0, to take on Karlo Ledesma in the semifinal round.
Ledesma earned his semifinal ticket after defeating Bryan Mangapis, 6-1, 6-2.
The other semifinal match will be played between Dan Eldren Cinco and Kurt Gerapuso.
Cinco outplayed Kim Ayuda while Gerapuso dumped Marion Mendoza, 6-2, 6-3.
On the other hand, University of the Visayas' Cyril Camporedondo continued to pounce on and entered into the quarterfinal round of the boys' 16-under division.
Camporedondo beat Maki Bundaug, 6-3, 6-1, to meet Reymond Padigos next.
Padigos earlier clobbered Aljen Olivar, 6-0, 6-3.
Ronaldo Espina also grabbed a quarterfinal seat in the 16-under.
In the 14-under class, those who secured quarterfinal seats are Princeston Gerapuso, Aaron Ronca Espina, Joseph Tallo, Arc Montecalvo, twins Christian Paul and Christian John Cabahug and Anito Prieto.
The 10-under unisex division, on the other hand, saw Mark Schroder, Ralph Julianne, Necesario and Trisha Mae de Claro.
Lone female netter de Claro pulled a hard-earend, 6-3, 7-5 win against Shutaro Kobayashi to get into the quarterfinal battle.