title: Ateneo–La Salle rivalry
context: La Salle and Ateneo were co-founders of the NCAA but now compete in the UAAP. The seed for a future rivalry was planted after an Ateneo loss to La Salle in the championship game of NCAA season 16 (1939–40). Games between Ateneo and La Salle in the NCAA were always hotly contested but not yet tagged by the sportswriters as a rivalry since the recognized rivalry then was between Ateneo and San Beda, and La Salle and Letran. When Ateneo and La Salle transferred to the UAAP 1978 and 1986 respectively, they continued their hotly contested games and the sports press started to write about a rivalry. The basketball games between Ateneo and La Salle are currently the most anticipated in every UAAP season. These games draw huge crowd of students, school faculty/ officials, alumni, actors and actresses, musicians, business tycoons, high government officials such as cabinet members, senators, congressmen and justices of the Supreme Court also Former presidents of the Philippines and ambassadors of the United States of America also attend the games. Both schools have extended their rivalry into the academic field and other sports.
question: When did the Ateneo–La Salle rivalry begin?
answers: 1939–40