Sometimes history is the best guide.

Norcross and McEachern played a high-stakes basketball double-header on Wednesday night to determine semifinal boys and girls teams in Class AAAAAAA.

The teams with the lower rankings but the most titles – Norcross’ boys and McEachern’s girls – won out.

In the opener, McEachern’s four-time defending-defending girls looked vulnerable despite a 14-game winning streak. Ranked No. 6, they were missing three starters, two that suffered knee injuries in the quarterfinals. Norcross was 26-3, ranked No. 3 and playing at home with a 14-game winning streak of its own.

The champions started two freshmen and lived to tell, winning 67-62 in overtime, their 23-game winning streak in the state tournament intact. McEachern is still in position to break the girls’ record for the most consecutive titles in the highest classification held with Lowndes (1977-80)

The boys game was even more surprising.

McEachern entered looking almost unbeatable, with several top-10 national rankings, an undefeated record against Georgia teams and eight wins over out-of-state teams (including national power Simeon of Chicago), but one was thing missing – a state title. Norcross, with five state championships since 2006, jumped to a 24-8 lead after one quarter on its home court and rolled the Indians 75-55.

Both winning teams enter Saturday’s semifinals at the Buford City Arena as the teams with the most tradition, and its not close.

Norcross’ boys are joined by Newton (last title 1964), Meadowcreek (never won) and Grayson (never won).

McEachern is the only girls team in the final four with state-title hardware. The others are Newton, North Forsyth and Westlake.

For more on the Norcross-McEachern games, read Stan Awtrey’s coverage of the girls game and the boys game on ajc.com.

Here are more observations from the quarterfinals and beyond …

Newton sweeps

Newton’s boys and girls teams are in the semifinals. The boys defeated Wheeler 87-81 and made the semis for the fourth time since 2005. The girls defeated fourth-ranked Cherokee 70-68 and are in the semis for the first time since 1963. That’s a great accomplishment, although not unprecedented as McEachern and Norcross qualified both teams to the semifinals last year.

Westlake proves 7A blog wrong

Westlake is ranked No. 1, but it was No. 2 Collins Hill that was the choice of this blog to win the state title. Wrong, by 25 points. Westlake, a perennial contender but never a champion, routed the Eagles 58-34 on the road. Freshman point guard Raven Johnson had 11 points, seven rebounds, five steals and four assists. Westlake will face North Forsyth on Saturday while McEachern battles Newton.

Hurrah for Gwinnett’s boys

Three Gwinnett County boys teams are in the semifinals. They are Norcross, Meadowcreek and Grayson. This is Norcross’ eight semifinal since 2005, and the Blue Devils are 7-1 in semifinal games in that time. It’s Grayson’s second in two years. It’s Meadowcreek’s first semfinal. The last time that one county put three boys teams in the semifinals was 2013, when Wheeler, North Cobb and Hillgrove made it from Cobb. The boys matchups Saturday are Newton vs. Norcross and Meadowcreek vs. Grayson.