Buddy Peoples of Crofton chipped into the cup to defeat defending champion Gary Marlowe of Woodmont, 3 and 2, in a quarterfinal match, and later sank a 12-foot par putt on the first extra hole to turn back 16-year-old Jim Estes of Manor in an afternoon semifinal of the Maryland Amateur golf championship yesterday at Woodmont.

Peoples will face Marty West of Columbia in the scheduled 36-hole final starting at 9 o'clock this morning. West will be in quest of his fifth Maryland Amateur.

Peoples, who resides in Crofton, is staying at Marlow's house in nearby Rockville during this tournament. He threw the damper on his host by chipping into the hold for birdie from heavy rough to end the match on the 16th green. "That clover was seven inches deep, I guarantee you," said Peoples, a 31-year-old computer specialist who has been living in this area for three years.

"It was one of those days where neither of us played really well," said Peoples, whose biggest career golf victory was the 1977 Virginia Beach Amateur. Peoples was three over par and Marlowe was all over the golf course and eight over.

"I hate to beat the guy," Peoples said. "One of us had to win and one of us had to loose. He even bought me lunch and invited me to dinner if I won the afternoon match," which Peoples did.

He evened his match with Maryland junior champ Estes, a senior-to-be at Peary High, when Estes hooked his tee shot into a water hazard on the 17th hole and took double bogey.

They halved the 18th hole in par to force the playoff. In the playoff, Peoples hit his tee shot into a sand trap and hit his second shot short of the green on the par-4 hole. Estes struck his approach shot over the green. Peoples wedged to within 12 feet of the hole. Estes chipped 15 feet short of the cup, missed the putt and took bogey. Peoples made his 12-footer for par to win the match.

West ousted medalist Tom Walsh of Montgomery Village, 3 and 1, and then methodically eliminated Jerry Freishtat of the University of Maryland, 4 and 2, in the afternoon. The 32-year-old Walker Cup player and former Masters and U.S. Open participant shot par for the day.

West, who owns a home bordering the third fairway, had early difficulty against Freishtat. Freishtat won the first hole with par and went two up with a 15-foot birdie putt on the fourth hole. West won the sixth hole with par and squared the match when he chipped into the cup from 45 feet for birdie at seven, the fifth straight time West has birdied that hole this week.

Freishtat had trouble avoiding the rough on the back nine. He took bogey from the high grass at the 10th hole and fell three down when he took another bogey from the weeds at 12. The match came to a close at 16 when Freishtat made bogey 4 and conceded a three-foot par putt to West.

Freishtat had won the last three holes of his morning match to edge Mike Toomey of Bethesda, 1 up. Estes eliminated Brad Pritchard of Congressional, 3 and 1, in his quarterfinal.