Followers of the Alhambra Catholic Invitational basketball tournament traditionally expect a strong showing from representatives of the Washington Metropolitan Athletic Conference. So there was little surprise that defending champion De Matha and Mackin easily advanced to Saturday night's contest at 8 p.m.

De Matha (26-0), the nation's top-ranked high school team, will try for its fifth Alhambra crown after breezing past Fast Judge of Philadelphia, 63-40, at Frosburg State Colleges' physical education center. Mackin (25-4), twice a winner here, had little trouble disposing of host Bishop Walsh of nearby Cumberland, 59-42, in an earlier semifinal Friday 18th title contest at 8 p.m.

De Matha, winner of 32 consecutive games, needed the first quarter to figure out Judge (28-4). Then the Stags, who trailed, 8-7, after one quarter, outscored the Crusaders, 24-4, in the next eight minutes; 10 points from Charles Branch provided a 31-12 intermission bulge.

The Stags' pressing man-to-man defense forced eight turnovers in that span.

The Stags quickly extended their lead to 38-16 with 3:29 remaining in the third quarter and Judge never came within 19 points after that.

Mackin outpointed Walsh, 18-2, in the first five minutes of the second quarter for a 28-9 lead. The outcome was never again seriously in doubt.

Walsh (17-7), harassed by Mackin's pesky man-to-man defense and the Trojans' superior height, connected on only five of 31 first-half field goal attempts. The Spartans made the mistake of driving inside against the bigger Trojans and consistently came up with more backboard than basket.

Kevin Black, Mackin's 6-5 center blocked three Walsh shots in the first half and finished with 13 rebounds, high for both squads.

Walsh made one charge at Mackin late in the third quarter. Kevin Carcella scored eight points as the Spartans registered the last six points of the third quarter and opened the final eight minutes with four points to cut Mackin's advantage to 40-34 with 6:37 to play.

Black accounted for five straight points for Mackin and Walsh could pull no closer than nine points.

Richard Crooks led the victors with 18 points with 8 for 13 shooting. Teammates Mark Nickens made 6 of 10 field goal attempts and finished with 13 points.

Carcella was the only player to score in double figures for Walsh, 18.