Aruhappy and Cousin Wes, the 1975 and 1976 winners, respectively, will go the post Saturday in the Potomac Cup, the three-mile timber steeple-chase that is expected to lure a crowd of close to 10,000 to Belvedere Farm for the 25th annual Potomac Hunt point-to-point meeting.

A little later in the afternoon Portobello III, Idol Fellow and Jay's Trouble are scheduled to take the flag in the Potomac Plate over the same course. Portobello III won the race in 1973, Idol Fellow in 1975 and Jay's Trouble last year.

Both races are key stops on the spring point-to-point schedule, the cup counting toward the Seven Corners Challenge Trophy and the plate toward the Governor's Cup.

Potomac's seven-race will open with the Travilah Challenge Trophy, a maiden hurdles that has drawn such promising young jumpers as Known Royal, Ginger Phar, Sure Move and I Achieve. The Anne Christmas Memorial, a hunting-pair event, is scheduled for 11 a.m.

The Potomac Plate could break the tie between 16-year-old David Myers of Upper Marlboro and Jay Griswold, the veteran Cockeysville, Md. rider, for the lead in the Governor's Cup, emblematic of Maryland's point-to-point title. Both riders have eight points.

Belvedere Farm is on Travilah Road, two miles past the village of Potomac.