Mater Dei won a coin toss and will play host to Riverside Poly on Tuesday in the second round of the Southern Section 5-A baseball playoffs.
The Monarchs are attempting to become the first school in Southern Section history to win football, basketball and baseball titles in the same season.
Irvine also won a coin flip and will play host to Riverside Arlington in the 4-A playoffs Tuesday. The key game in the division will be Canyon at Fullerton.
Tuesday's playoff games involving Orange County teams (all games begin at 3:15 p.m.):
Diamond Bar (25-1) at Fountain Valley (16-12); Royal (18-7) at El Dorado (21-5); Riverside Poly (20-6) at Mater Dei (22-4); Bishop Amat (20-5) at Cypress (14-12-1).
Arlington (19-7) at Irvine (17-10); Arroyo Grande (17-4) at Sunny Hills (15-12); Capistrano Valley (21-5) at South Hills (16-9); Canyon (18-7-1) at Fullerton (18-7); San Luis Obispo (14-8) at Savanna (13-13).
Norco (20-7) at Laguna Hills (19-8); Tustin (18-7) at Central (14-6-1); Garden Grove (15-8) at Apple Valley (17-6).
Oak Park (13-9) at Orange Lutheran (19-4).
Small Schools Division
Oakwood (7-7) at Calvary Chapel (12-7).