TENNIS: H.-W. PAIR ADVANCE TO SEMIS.

Byline: Erik Boal Special to the Daily News

Fifty down, four to go.

After going undefeated through 20 matches and four rounds in the Southern Section girls' individual tennis tournament, all that stands between Harvard-Westlake of Studio City seniors Amber Harper and Jennifer Kaswick and a doubles championship are four more victories.

Despite a 12-day layoff since qualifying for the round of 16, the Mission League champions showed no signs of a letdown. They posted two convincing victories Thursday to lead a list of five local athletes - with the possibility of a sixth today - to secure berths in the semifinals.

Harper and Kaswick joined league runners-up and sisters Aimee and Erynne Oki of Notre Dame of Sherman Oaks in the doubles semifinals, with the possibility of the teams meeting in the first all-local final in the tournament's 34-year history when play begins at 10:30 a.m. today at Seacliff Country Club in Huntington Beach.

The Oki sisters, who reached the quarterfinals last season, defeated Peninsula of Rolling Hills Estates' Emily Aston and Stephanie Chen 6-3, 6-3 to earn a matchup with Troy of Fullerton's Samantha Nadres and Alison Ramos.

Harvard-Westlake sophomore Hilary Barte reached the final four in singles with two straight-set wins, but Campbell Hall of North Hollywood senior Ally Krasnopolsky had her quarterfinal match against Peninsula's Tania Mahtani suspended because of darkness. The two will resume their match at 9 a.m. tied at a set apiece to determine the last semifinal berth.

Fortunately for Harper and Kaswick - who will face Jill Damion and Allie Walters of Corona del Mar of Newport Beach in the semifinals - they had no such problems.

``We're feeding off our undefeated record and I think other teams know it as well,'' said Harper, whose sister, Calabasas freshman Brittney, lost with partner Eileen Chang in the round of 16.

Kaswick, Harper and Barte also are bidding to become the first athletes from the same school to win the singles and doubles titles since Peninsula accomplished the feat in 1993.

``We're confident with our games and how we're playing,'' Kaswick said. ``It's a nice little goal to keep going for. (The title) is something we want.''

Barte, who defeated Brittany Blalock of Palm Desert and Troy's Clarissa Fermin, said: ``It's very gratifying. I just feel like it's my time.''