Harvard-Westlake (27-1), the two-time defending state champion, received the No. 1 seed for the Southern Section Open Division boys’ basketball playoffs Saturday. Ten teams were selected, with the tournament broken down into two five-team pools.

It’s the first time computer rankings were used to place teams in divisions. In previous years, teams knew their divisions before the season based on the previous two years of performances, then advisory panels helped create seedings. Now teams are put into divisions based on their rankings using an algorithm by sports technology and media company SB Live Sports. No wild-card games are being played.

Harvard-Westlake opens the playoffs with a home game against No. 9 La Mirada on Wednesday and will host throughout pool play that ends Feb. 25. Also in the Wolverines’ pool are No. 4 Santa Margarita, No. 5 Sherman Oaks Notre Dame and No. 8 JSerra. No. 2 Eastvale Roosevelt leads its pool with No. 3 St. John Bosco, No. 6 Sierra Canyon, No. 7 Redondo Union and No. 10 Heritage Christian.

Roosevelt hosts St. John Bosco on Feb. 25 in a possible pool decider. The two pool winners meet the following week for the Open Division title. Also only eight of the 10 teams are guaranteed state playoff games, so a tiebreaker procedure is in place, starting with wins/losses in the pool, then head-to-head matchups.

For Open Division girls, the new kid on the block, 25-1 Ontario Christian, received the No. 1 seed for an eight-team bracket that includes two-time defending state champion Etiwanda, which is seeded No. 2 after winning its 25th consecutive Baseline League title.

In Ontario Christian’s pool are No. 4 Sierra Canyon, No. 5 Bishop Montgomery and No. 8 Sage Hill. Ontario Christian hosts Sierra Canyon on Feb. 22. Etiwanda’s pool includes No. 3 Mater Dei, No. 6 Windward and No. 7 Fairmont Prep. Mater Dei has been weakened by an injury to Kaeli Wynn, one of its best players.