Yorktown's boys basketball team upset South Lakes to tighten the Great Falls District race. The Patriots wrestling squad remained unbeaten in the district, setting up a big matchup with defending champion Marshall, next Wednesday at Marshall. Another girls basketball team was victim of the upset bug as W.T. Woodson was knocked off by Oakton. Boys Basketball

Mount Vernon, Lake Braddock and Annandale each won to remain on top in their respective districts while Yorktown upset South Lakes to create a tighter Great Falls District race.

Lorenzo Bryant had 19 points to lead Mount Vernon past Gunston District rival Edison, 81-56, for its 13th straight win. Lake Braddock downed West Springfield behind 35 points from Hubert Davis. The Bruins' 85-75 victory coupled with Robinson's 63-61 upset of T.C. Williams put Lake Braddock alone in first place in the Northern District. Annandale handled Jefferson, 92-64, and Falls Church, 94-62, with ease to take a two-game lead in the Potomac District.

Yorktown took advantage of foul trouble to South Lakes' standouts Grant Hill and Jerome Scott to knock off the Seahawks, 72-67. Terrence Knuckles had 26 points as Yorktown moved to within one game of the district lead with a 79-62 win over Marshall last Friday. Girls Basketball

South Lakes remained on top in the Great Falls District with victories over Yorktown and Langley. Terri Bradley had 29 points in the victory over Langley.

Annandale and Lee also remained unbeaten in the Potomac and Gunston Districts. The Atoms easily defeated Falls Church, 69-38 and Jefferson, 97-25 as Ann Marie Kennedy scored 44 points in the two games. Ashley Hancock had 18 points to pace a balanced Lee attack in a 70-28 win over Hayfield.

Lake Braddock, led by 15 points from Laura Teter, downed West Springfield, 65-41, to hand the Spartans their first Northern District loss. W.T. Woodson also suffered its first district defeat, losing to Oakton, 61-55.

Bishop O'Connell's girls team improved its record to 12-1, defeating Regina, 48-32. Erin Hollister led the way for the Knights with 20 points. Wrestling

Charlie Schollaert and Kevin Madden each scored pins to lead Yorktown to a 45-20 win over Herndon. The win kept the Patriots unbeaten in dual matches. Earlier in the week, Yorktown routed South Lakes, 62-6. Herndon, which also defeated McLean last week, was led by Jay Troxell. The 168-pounder remained unbeaten in his class with a pair of victories.

Marshall ran its dual meet win streak to 12 with three victories in the Madison quad meet over the weekend. The Statesmen routed Edison, 56-4, Stuart, 60-6 and easily outdistanced Madison, 49-18.

Robinson won the final nine weight classes, five by pins, to easily defeat Lake Braddock, 54-11, in a Northern District match. Hayfield won 10 of 13 matches to dispose of Gunston District rival West Potomac, 49-13 and Annandale routed Falls Church, 51-19, in Potomac District action. Gymnastics

West Springfield placed second in the Park View Invitational behind North Stafford of Prince William County, 107.25-102.5. The Spartans were led by Rachel Griffin (see profile). Lake Braddock finished fifth with 99.7 points despite an injury to their top gymnast Misty Minger, who is out indefinitely because of a skiing injury. Mount Vernon's Regena Oelrich finished second in the all-around behind North Stafford's Mindy Berg with 35.75 points. Oelrich, a senior and the only gymnast representing Mount Vernon in the meet, was first on the uneven bars (9.4), fourth on the balance beam (8.8), sixth on the vault (9.0) and eighth in the floor exercise (8.55).

West Springfield's depth keyed a quad meet victory last week over Herndon, Fairfax and Lee. The Spartans' Leigh Ullman and LeeAnne Revell each won events and Griffin, on the strength of two second place finishes, won the all-around competition. The Spartans' total of 165.6 was 34.3 points ahead of runnerup Herndon.

Chantilly beat out Fairfax, Falls Church and Broad Run of Loudoun County to win a quad meet. Blake Ford of Chantilly finished second in the all-around competition with a 31.3 total, winning the uneven bars with a score of 8.2. Jenny Kinzli of Falls Church captured the floor exercise and vault competitions, but a lack of depth kept the Jaguars (31.2) far behind Chantilly's total of 122.2. Fairfax, led by all-around winner Missy Dyer (32.9), finished second with a 118.9 team total. Volleyball

George Mason's girls volleyball team had won just nine matches in the past five years. But this year, after a win over Brentsville, the Mustangs are the Bull Run District's surprise team with a 7-0 mark.

The Mustangs won just one match in the three seasons before current coach Al Krueger took over. They won three games each of Krueger's first two seasons, but are now on the rise with a mix of underclassmen and one senior. Senior Jenny Boozel, the Virginia A state girls tennis singles champion, has been a leader both in the serving and spiking categories. Sophomore Linda Tran and junior Susan Miller have also keyed the Mustangs' success. Indoor Track

Most Northern Region teams did not fare well at the seventh annual Blacksburg Civitan track and field meet at Virginia Tech last weekend, but several individuals turned in some outstanding performances. Mount Vernon's James Colbert's 49-1 triple jump qualified for state competition. T.C. Williams, which finished second in the girls meet, was led by Jennifer Seltz who captured the 3,200 meter run after finishing second in the 1,600 meter run by one second.

Fairfax won its dual meet with McLean. The girls, led by Dorophea Ku (a winner in both shotput and 55-meter hurdles) and Gina Perry (who qualified for state competition with a high jump of 5-2), won, 85-22. The Rebels' boys squad also won impressively, handling McLean, 58-23.