Gary Marlowe of Woodmont moved into the semifinals of the Montgomery County Sentinel Junior Golf Championship at RedGate yesterday.

Two other pretournament favorites, Jack Skilling of Chevy Chase and defending champion Clay Fitzgerald of Kenwood were eliminated. Skilling lost in the quarterfinals to Tom Loveless of Argyle and Fitzgerlad was ousted by Dean Webb of Washington in the morning round.

Marlowe will play John Miller of Manor in the first 18-hole match this morning and Loveless will take on Dan Bosis of Indian Spring. The championship will be at 18 holes this afternoon.

Marlowe beat Reagon O'Rourke in the morning and whipped Webb, 5 and 4, in the afternoon. Marlowe was 1 up on Webb after nine holes. Marlowe won the 10th with a par and the 11th was halved with birdies. Marlowe won the 12th and 13th with pars to go 4 up, then birdied the 15th to end the match.

Miller defeated Mark Donohue in the morning, then beat Charles Gates of Columbia, 4 and 3. Miller was 1 up at the turn and won the 11th and 13th with pars and the 14th with a birdie. The 15th was halved.

Loveless, who beat Marlowe in the District junior championship last week, was even with Skilling after nine holes. The 16-year-old Loveless, a Good Counsel High School student, then won the 10th with a par and the 11th with a bogey to go 2 up. Skiling won the 13th with a par but Loveless parred the 17th for the match, 2 and 1.

Bosis, 16, a Springbrook High School football player, had to rally after being 3 down at the turn to Kelly Elbin, son of Burning Tree pro Max Elbin.

Bosis won the 10th and 11th holes with pars but lost the 12th. He won the 13th and 14th to pull even, and went ahead for the first time when he won the 17th with a par. A half on the 18th won it.

Vikki Staton of Alexandria turned back Pat Crew of South Boston, 3 and 2, and Liz Waynick, a 1976 finalist, overwhelmed. Bert Diservio of Richmond, 6 and 5.