Monday marks the beginning of the most significant week of the high school seasons so far. There are three nights of high school football playoffs, after which the number of teams still alive will be cut by more than half, along with the quarterfinals of the soccer state tournament and the girls' tennis state tournament.

Here's a look at a few of the more significant things to look for.

FOOTBALL

The playoff pairings were determined through a system devised by Minnesota-Scores.net called Quality Results Formula, or QRF. Like all statistics-based formulas, it is based on quantifiable numbers and doesn't take into account such things as injuries, matchups or weather, but it has proved valuable as a way to avoid disputes in terms of seeding.

The first round of Class 6A football is Friday. The rest of the classes will play first-round games Tuesday and semifinals Saturday.

A complete list of first-round sectional matchups can be found in Sunday's paper. Most were hard to argue, but two raised legitimate questions.

• Section 5, Class 6A: While Maple Grove and Totino-Grace were no surprises as the Nos. 1 and 2 seeds, Centennial (6-2) got seeded No. 3 over Osseo (5-3). Centennial's record was clearly better, but Osseo played a tougher schedule. Both of the Cougars' losses were to Class 5A teams (Elk River and Spring Lake Park) while all of Osseo's losses were to Class 6A schools (Minnetonka, Eden Prairie and Totino-Grace). And the Orioles can boast a victory over a top seed (Maple Grove).

• Section 6, Class 5A: Rogers (7-1), despite its only loss coming by one point in the final 2 minutes at St. Michael-Albertville, received the No. 3 seed, behind No. 1-seeded St. Michael-Albertville (7-1) and Elk River (6-2). The Elks were awarded the No. 2 seed because they played six games against Class 6A teams, going 4-2. So Rogers hosts Willmar on Tuesday while Elk River gets a first-round bye.

SOCCER

Boys

Class 2A: There were no surprises with East Ridge, Maple Grove, Minnetonka, Wayzata and Rochester John Marshall earning seeds 1 through 5, respectively. The possible matchup of note would come in the semifinals, where undefeated Maple Grove (19-0) could face another undefeated team, Minnetonka (16-0-2), should both survive their quarterfinal games.

Class 1A: DeLaSalle, making its first state tournament appearance, earned the No. 1 seed. For the Islanders (17-1-1) to reach the championship, they'll have to beat Mahtomedi (12-3-4), a team with six previous state tournament appearances, and then would have to get past either Chaska or defending champion St. Paul Como Park in the semifinals.

Girls

Class 2A: South Suburban Conference teams earned the No. 1 and No. 2 seeds. The only blemish on top-seeded Eagan's 18-0-1 record is a September tie with Eastview. No. 2 seed Lakeville North's (15-2-1) only losses are to the top seeds in the tournament. The Panthers lost to Minneapolis Washburn, the No. 1seed in Class 1A, 1-0 and to Eagan 2-0.

Class 1A: Washburn (18-0), making its first tourney appearance since 1992, is proving that a team cannot lose if it doesn't allow its opponent to score. The Millers, who won the 1981 state championship and was runner-up in each of the three succeeding years, have shut out 15 straight opponents and have not given up a goal since a 4-1 victory over Visitation on Aug. 28. The most likely threat to Washburn looks to be Sophie Babo and No. 2 seed Orono. The Millers beat the Spartans 1-0 on Sept. 15.