Samantha Porter and No. 5 Mount Vernon, the AAA National District champion, will be hard to bring down in the Northern Region. (John McDonnell/THE WASHINGTON POST)

Here’s a look at the first-round Virginia AAA Northern Region matchups. The tournament begins Monday night and continues Tuesday with the quarterfinals, Thursday with the semifinals and Saturday with the championship. The semis and final will once again be held at Robinson. The two finalists qualify for the state tournament.

Because of Virginia High School League realignment, this will be the last Northern Region tournament in its current form, at least with the full complement of schools that have been long been associated with the region.

Next school year, 21 of the current Northern Region schools will play in 6A North, a group that might retain the Northern Region name. The other nine region schools (Jefferson, Marshall, Edison, Falls Church, Mount Vernon, Stuart, Wakefield, Lee and Stone Bridge) will play in 5A North and not meet the 6A teams in the conference playoffs.

The first-round pairings:

Robinson (7-16) at Madison (17-8): Two teams in somewhat surprising positions. Robinson won just one Virginia AAA Concorde District game during the regular season but in the district tournament the Rams were able to top Westfield, a team they had lost to by 17 and 22 points. Madison won the Liberty District tournament championship having weathered the season-ending off-season knee injuries to their two leading scorers from a year ago. If the district tournament were any indication, the region tourney should make more followers aware of the clutch play of Madison senior guard Megan LeDuc, who in three Liberty tourney games scored 65 points and made two-game winning shots. Madison beat Robinson in the region quarterfinals last season.

W.T. Woodson (13-12) at No. 14 Edison (20-4): Edison might be one of the more intriguing teams in the field. The Eagles own wins over ranked teams Calvert, Potomac (Va.) and Bowie and also over Patriot District champion T.C. Williams. They have not lost locally, other than to Mount Vernon. But three of the team’s top five scorers are freshmen, and there’s only one senior on the roster, forward Sheila Sherrill, the team’s leading scorer. W.T. Woodson is capable, particularly if senior guard Keara Finnerty is on. She scored 40 points last week in Patriot District semifinal upset of West Springfield. This is the teams’ fourth postseason meeting since 2004.

Wakefield (12-11) at West Springfield (20-4): In a typical season, this first-round matchup would stand out as a mismatch. And maybe it will be. But Wakefield lost this season by four to T.C. Williams, by six to Edison and by four to Mount Vernon. West Springfield, with two freshmen among its top three scorers, has been vulnerable. At the same time, would anyone be stunned to find even a rebuilding West Springfield team back in the region final for a fourth straight year?

Fairfax (16-8) at No.12 Centreville (22-2): This game features two of the best point guards in the region, with Fairfax junior Kylie Murphree and Centreville junior Jenna Green. Green and the Wildcats enter the postseason having beaten Oakton twice in 11 days after not knocking off the Cougars since 1995. Centreville topped Fairfax, 58-35, on Dec. 7. Fairfax has wins over six region qualifiers — Chantilly, Woodson, Robinson, South Lakes, McLean and Madison.

Washington-Lee (13-11) at T.C. Williams (17-8): Patriot Distict champion T.C. is the only team among the 16 qualifiers to have three players who have scored at least 25 points in a game this season — sophomore guard Rejoice Spivey, senior guard Christian Roberts and junior guard Angie Schedler. Half of the team’s losses have been to ranked teams Edison, Potomac (Va.), North Point and Stonewall Jackson. Washington-Lee, led by junior guard Tatianna Torres (18.3 ppg), has its most wins since the 2002-03 season. The Generals have only one victory this season over a region qualifier, that coming in a split with Wakefield. T.C. and W-L have not met since 2004.

McLean (18-7) at Oakton (20-4): McLean had a chance to win its first Liberty District title but lost in the final to Madison, after rallying from to tie the score with about 17 seconds left. Senior Lisa Murphy has been a consistent force for the Highlanders, scoring in double figures the past 19 games, including a career-high 27 points in the Liberty final. Oakton, led by senior center Elizabeth Manner (24.1 ppg), is in retooling mode but has won three of the past four region titles. The Cougars, like West Springfield, are more vulnerable than in recent seasons, but their advancing to the region final would not be a huge surprise given the track record of winning five region titles since 2001, with a runner-up finish in 2007.

Chantilly (9-15) at South Lakes (20-4): The homestanding Seahawks, ranked for much of the season, lost twice this month to Madison, but their four losses are by a total of 11 points. South Lakes junior center Abigail Rendle is coming off a season-high 25-point scoring night against Madison. Chantilly’s wins have come against teams with a combined 40-93 record. South Lakes and Chantilly met on Dec. 1, with the Seahawks prevailing, 68-37.

Lake Braddock (16-6) at No. 5 Mount Vernon (21-2): Mount Vernon, which has not lost locally this season, enters the tournament as the favorite, even though it has not reached a region final since 2000. Even as a fourth seed vs. first seed game, this is not an easy draw for the Majors. Lake Braddock boasts 6-foot-4 Natalie Butler, a Georgetown signee averaging 26.2 points. Mount Vernon boasts the superior roster, led by senior guard Kelly Loftus, but has no player taller than 6 feet.

Herndon edged Robinson, 51-48, and Centreville beat top-seeded Oakton, 44-41, to win Virginia AAA Concorde District basketball championships at Robinson. (Abigail Fazio for Synthesis/Koubaroulis LLC/The Washington Post)