Living up to his top billing in this event presented by Dunlop and Accel, Arcilla, 22, gave Lazaro little room to operate with his booming forehand winners for the win that set him up against fifth seed Lee Chang Hoon of Korea.
Lee led the Korean charge as he overcame a stiff challenge from No. 12 Antonio Sagansay, 6-4, 1-6, 6-2, in a fierce battle that lasted an hour and 45 minutes.
"Inunahan ko na agad siya para hindi na makaporma," said Arcilla, who has yielded only four points in his last three matches.
"Maganda ang panalong ito kasi kahit papaano naka-conserve ako ng energy going into my game against the Korean tomorrow (today), " he added.
In womens play, top-ranked Czarina Mae Arevalo waylaid Julie Ann Cadiente, 6-3, 6-1, to jump into the final eight amid the Korean juggernaut in No.3 Kim Soo Jin and No. 4 Lee Min Hee.
Kim walloped Karen Reyes, 6-1, 6-0, while Lee pummeled Ziarla Battad, 6-2, 6-1, to join Arevalo in the next round.
Another Korean standing on Arcillas path is Chung Eui Hyun, who outlplayed national coach Cris Cuarto in another marathon three-setter, 5-7, 6-3, 6-3, that took them two hours and 25 minutes to finish.
The 27-year-old Chung, whose last singles title came nine years back in a juniors tournament back home, started the game flat to yield the first set before recovering in the second and third sets to escape with the win.
"He got tired. I was tired too but I concentrated well and recovered my strength in the second and third sets," said Chung, who edged Ateneos Neil Co, 7-5, 0-6, 6-1, before this round, through an interpreter.
The deciding point came in the fifth game of the third set when Cuarto, seeded 10th in this meet supported by The STAR, Coca-Cola, San Miguel, PBCom, Photokina, Equitable-PCI, PVL Restaurant-Little Lawrence, Copacobana and Trans Asia Power, bungled five game points that enabled Chung to hold serve, paving the way for the Korean to take control.
A native of Chonan, a southern province two hours from capital Seoul. Chung faces 19-year-old and third pick Joseph Victorino in todays quarterfinals. Victorinos foe, Pio Tolentino, retired before the fourth game of the second set started due to an ailing right foot after trailing, 0-6, 0-3.
In the battle of young guns, 11th seed Nino Salvador stunned eighth seed Pop Sabandon, 7-6 (5), 6-4, while 17-year-old Pius Mendoza of Santo Tomas stopped Kyle Dandans giant-slaying ways while extending his own with a 6-3, 6-0 triumph.
While the Salvador-Sabandon game was the more fiercely-fought, it was Ocampo and Dandan, the youngest participant at 13 years old, who drew keen interest.
Last years UAAP rookie of the year, Ocampo, whose list of victims include No. 4 Michael Mora III, was just too good for Dandan, who shocked No. 14 Raymundo Lopez in the opening round, in a game witnessed by former Davis Cupper Felix Barrientos.
Dandan, a Grade 7 student of Colegio de San Agustin, got some pointers from Barrientos after the game and went home with one more task to fulfill as he is set to leave on Nov. 29 for the United States to compete in next months Orange Bowl, a tough international event for age-groupers in Florida. The other quarterfinal pairing pits No. 2 Adelo Abadia, who trounced 13th pick Luisito Clores, 6-3, 6-1, versus ninth seed Rolando Ruel Jr., who clobbered seventh ranked and doubles partner Jessie Lapore, 6-1, 6-1.
Other womens winners at presstime were Petrona Bantay, who downed Sommer Bisagas, 6-1, 6-0, Alyssa Labay, who scuttled Ma. Shirley Valler, 6-0, 6-1, and sixth seed Charise Godoy, who grounded Michelle Panis, 6-4, 6-2.