Rob Sanz took charge for PCU in the third quarter as he knocked in three triples and went on to fire 22 points to power the Dolphins to their 10th victory in 13 outings and claim the No. 2 spot for the team in the semifinals.
"Lahat ng ginawa ng players ngayon, hindi para sa akin, para kay coach lahat ito," said interim PCU coach Joel Dualan, who took over the chores for Junel Baculi, who was suspended for one-game for his misconduct during the PCU-San Sebastian game last week.
The win thus gave the Dolphins the other twice-to-beat advantage in the semis.
Earlier, Letran shackled San Sebastians top guns Leo Najorda and Red Vicente as it fashioned out a 65-46 rout to claim the top spot in the next round.
Jonathan Aldave sizzled with 16 points but it was the Knights tough defense on Najorda and Vicente that anchored their victory, their 12th against one loss. Najorda and Vicente struggled for a combined 16-point output.
"Sabi ko sa kanila na hindi dapat natatalo ang champion team ng dalawang sunod kaya na-challenge siguro sila," said Letran coach Louie Alas.
Aldave scattered all but two of his total output in the first half as he powered the Knights to a 38-22 lead at the turn. The 2003 champions made it a 56-35 advantage at the end of the third period with Letrans Four As Aldave, Aaron Aban, Mark Andaya and JP Alcaraz doing most of the damage.
The loss, their sixth against seven wins, dashed the Stags bid for a twice-to-beat advantage in the semis.
Mapua took its fifth setback against eight wins.
After a Gabby Espinas basket gave the Dolphins a 19-16 lead early in the second quarter, Kelvin dela Pena banged in a triple to cap a 7-0 blitz that gave the Cardinals the upper hand, 23-19.
The 2004 rookie MVP struck back with a pair of drives as he sparked a run that gave back PCU a 33-30 lead and control at the break.
Then came Sanz, who fired three triples in an 11-0 binge as the Dolphins seized a commanding 44-30 lead to start the third quarter.
PCU made it a 53-38 win-its biggest in the game-late in the period but skipper Joferson Gonzales spearheaded a counter-offensive that cut Mapuas deficit to just six points, 47-53, early in the final canto.