Skipper Genelyn Alemania and Khristine Basco delivered the most crucial blows as the Lady Knights sealed their second victory in seven outings to barge into the magic four alongside the Lady Pirates.
"Nagkaroon kami ng kaunting pag-asa sa panalong ito," said Letran coach Ernesto Pamilar. "Hopefully, masurpresa naming ang La Salle sa huli naming game sa Thursday."
The win also gave Far Eastern U a chance of advancing to the next round if it could win its last two matches over Lyceum and four-peat NCAA titlist San Sebastian, which is currently at third spot on 3-3 (win-loss) slate.
Letran appeared in disarray in the early goings when it trailed 8-14 in the first set but slowly but surely clawed back to even snatch a 16-15 edge, a lead Lyceum erased when it regained control 21-18.
Basco, Alemania and Joana Marie Fernando rebounded by teaming up in a counter-offensive that saw the Intramuros-based belles taking eight of the final 11 points for a 1-0 lead.
That seemed to have pumped up Letran as it seized the second set and a 2-0 advantage by storm with superb court coverage and a rock-solid defense up front.
Maria Angelica Bigcas hammered through the Letran blockade with a barrage of powerful kills as Lyceum hung tough to take the third set, keeping its hope of snatching a win that would clinch the latter an outright seat in next weeks semis.
But the reigning WNCAA champions lost steam in the fourth set when Letran roared to a 22-14 upperhand.
Again, Lyceum fought back by cutting its deficit to three, 20-23, before Alemanias spike straight to the sideline and Bascos block on Bigcas attempted smash sealed Letran the triumph.