Boys When/Where: Tomorrow, Patriot Center, 7 and 9 p.m. First game: T.C. Williams (23-3) vs. Chantilly (15-9).

History: The teams haven't met since January 2005, when T.C. guard Shawn Andrews, then a sophomore, scored 16 in a 75-74 win in Alexandria. Andrews is now a senior for the Titans, who have won six region titles, the most recent in 2001.

How they got here: Top-ranked T.C. Williams is unbeaten against Northern Region foes, having easily handled Mount Vernon in the first round and then crushing Westfield on Tuesday, its fourth win in four days. Chantilly was the third seed in the Concorde. The Chargers scored double-digit wins over Langley and West Potomac.

What to watch for:The Titans are the highest-scoring team in the region and can dictate tempo with a suffocating press. They are deep with many scoring options, namely Andrews, who averages 17 points per game. Senior 6-foot-8 center Mike Davis is the region's premier shot-blocker. Chantilly has won six of its past seven games. Senior guard Ben Wheeler is the team's top scorer and sophomore guard Justin May continues to improve.

Second game: West Springfield (19-5) vs. Wakefield (22-4).

History: There is no recent history between these teams, both seeded third out of their respective districts. The Warriors were 3-0 against Patriot District foes this season. Wakefield went undefeated in winning the region crown in 2005 before falling in the state semifinals. West Springfield won its only region titles over three consecutive seasons (1972-74).

How they got here: Both teams won a pair of road games, with Wakefield edging Lake Braddock (which handed West Springfield three of its losses) in the first round. The Warriors then stunned defending region champion Herndon in the quarterfinals.

What to watch for:Seniors dominate both teams' rosters. Wakefield senior George Johnson is a savvy court leader, averaging 21.5 points in the postseason. As a sophomore, he was the sixth man on the 2004-05 team that went 28-1. West Springfield lost twice to T.C. Williams in the regular season before earning its best win of the year Monday, upsetting the National District's top seed Edison. Coach Dick Wickline, seeking his first region title, is the most experienced coach in the Northern Region.

GirlsWhen/Where: Today, Patriot Center, 6 and 8 p.m.

First game: T.C. Williams (19-8) vs. Edison (26-1).

History: Edison won 69-46 on Dec. 5, scoring 13 consecutive points in the second quarter to break open a tie game. T.C. Williams cut the lead to two late in the third period. Doreena Campbell (UCLA) and Adria Crawford combined for 33 points.

How they got here: Patriot champion T.C. Williams beat National fourth-seed Wakefield, 71-46, in the first round and Concorde second-seed Westfield, 40-34, in the quarterfinals. National District champion Edison beat Patriot fourth-seed South County, 76-46, in the first round and Liberty runner-up Madison, 77-38, in the quarterfinals.

What to watch for: This is a rematch of the 2006 region championship game, won 50-31 by Edison, the Eagles' first region crown since 1978. Each team returned largely intact. Other than a six-point loss to Bishop McNamara on Dec. 30, Edison has blown out almost every team it has faced; the closest against a region team was a 16-point win over West Springfield in the season opener. O'Connell transfer Chasity Clayton (14.1 ppg) has added pop to an already formidable lineup. T.C. Williams struggled for a good deal of the Patriot season when sophomore guard Tierra Ruffin-Pratt (23.1 ppg) was out with a shoulder injury. She is back now in full force, fronting a mostly senior-less rotation. Edison Coach Dianne Lewis is a 1977 graduate of T.C. Williams.

Second game: Oakton (25-1) vs. Marshall (23-4).

History: None during the regular season.

How they got here: Concorde District champion Oakton beat Liberty fourth-seed Stone Bridge, 62-34, in the first round, and Patriot regular season champion Lee, 46-34, in the quarterfinals. Liberty champion Marshall beat Concorde fourth-seed Chantilly, 58-44, in the first round and Patriot third-seed West Springfield, 52-43, in the quarterfinals.

What to watch for: The game pits two of the best guards in the Northern Region, Oakton senior Jasmine Thomas (Duke), the second-leading scorer in state history, and Liberty District Player of the Year Nicole Harrison, also a senior. Oakton won region titles in 2001 and '05. The Cougars' only loss this season was to Virginia Beach school Princess Anne (25-1). Senior forward Ashley Abed joined Thomas on the all-district team. Marshall, which lost to Edison in the region semifinals last year, has won 19 consecutive games, thanks in part to solid post play from seniors Maya Al-Shingieti and KT Mesich.