The Cardinals clawed the Eagles, 70-66, while the Bombers bombed the Knights, 64-58, to join the University of the East Warriors and the San Beda Red Lions in the semifinals.
The Final Four is set Thursday in the same venue with the Cardinals and the Warriors clashing at 2 p.m. then the Bombers and the Red Lions slugging it out at 4 p.m.
Mapua, led by Raymond Tiongco with 24 points, erected a 21-point lead in the third quarter then fought off a late charge by an undermanned Ateneo side to arrange a semis showdown with UE.
Jai Reyes fired 20 points for the Eagles, who missed the services of coach Norman Black, assistant coach Jamike Jarin and players Rabbeth Al-Hussaini, Eric Salamat, Ford Arao and Johan Uichico. Black and Jarin are on vacation in the United States while Al-Hussaini, Salamat, Arao and Uichico did not play due to academic reasons.
"We played good defense. It also helped that they’re not complete," said Mapua coach Horacio Lim.
With their defense holding and their outside shots sinking, the Cardinals led by as many as 21, 49-28, but the Eagles waged a fight back in the final quarter.
A triple by Reyes capped a searing run that had Ateneo threatening at 65-66 with 42.6 seconds to go. Mapua overcame the scare though on baskets by Jason Pascual and Sean Co.
Earlier, Jose Rizal leaned on its steady foul shooting as it walloped 2004 NCAA champion Letran to continue to its improbable run, setting up a Final Four encounter with current NCAA titlist San Beda.
The Bombers made a killing on the free throw line, making 25 charities as against the Knights’ 13, as they scored another reversal following a 65-63 shocker over UAAP champs Santo Tomas Tigers Monday.
"Nobody expected us to be here because we’re just a wildcard bet, and we used that to our advantage," said Jose Rizal coach Ariel Vanguardia.
The Knights sorely missed the services of Boyet Bautista and Aaron Aban, who have graduated to the pros.