The Red Warriors stretched their perfect run to six, while the Blue Eagles chalked up their fifth victory in seven ties.
Reigning MVP AJ Lim, Josshua Kinaadman, Dolfo Barquin produced singles wins, while doubles specialists Rogelio Estaño and RJ Saga provided the other win for the back-to-back title-seeking Warriors.
Doubles players Luke Flores and Erj Gatdula, and AJ Rivero and Julian Dayrit shone, while singles standouts Ino Canlas and Marcen Gonzales also delivered for the Eagles.
While UE booked its second straight Finals appearance, Ateneo reached the title round for the first time since 2001.
The Warriors need to win their last two ties, including the March 11 championship preview with the Eagles, to claim the twice-to-beat advantage in the Finals.
An Ateneo win over UE will make the championship tie a best-of-three affair.