Henri deLozier of Silver Spring, Md., birdied the third extra hole to win his morning match but his hopes of gaining the U.S. Amateur quarterfinals were dashed yesterday when he lost his afternoon round-of-16 match to two-time Ohio State All-America John Cook of Dublin, Ohio, 5 and 3.

Marty West of Bethesda, Md., was beaten by Mike Peck of Kansas City, Kan. 2 and 1, and Wayne DeFrancesco of McLean, Va., was bounced by Bill Monneyham of Houston, 1 up, in the morning fourth-round matches.

In his morning 21-hole victory over Tom Carlton of Augusta, Ga., deLozier sank a 45-foot putt on the 17th hole to square the match and won on the par-3 third extra hole when he canned a 30-foot birdie putt.

Against Cook, who won the California Amateur at 17 and the Ohio Amateur this year, deLozier fell to three holes down in 20 minutes when the 20-year-old Cook opened with par, par, birdie.

DeLozier, a 31-year-old lawyer, crept within two by winning the eighth hole with par and the ninth with a 25-foot birdie putt.

DeLozier dipped to five down when he bogeyed 11 and 12 by missing short putts, and 13 when his approach shot went well wide of the green.

He stayed alive by notching a birdie on the par-3 14th but Cook brought the match to a merciful close when he scored par on 15.

"I got real tired," said deLozier, who played a total of 36 holes.

"I think he was a little rushed after playing extra holes in the morning," offered Cook, who plays out of Jack Nicklaus' Ohio course, Muirfield Village. Cook was one under par against deLozier.

West, who like deLozier, plays out of Columbia Country Club, wrestled with an errant driver most of the morning, but it was two iron shots, which went over the 11th and 12th greens, that cost him dearly.

West air-mailed the par-3 11th green and Peck, who captained Stanford's golf team, evened the match with birdie.

On the par-5 12th, West was again strong with an iron shot. His lofted approach shot hit the green and trickled into rough, leaving him a difficult chip. He lost the hole to Peck's par.

Peck won his third straight hole when he scrambled for par and West bogeyed from a green-side trap on the par-4 13th. They halved the next three holes and Peck won on the 17th when both registered regulation pars.

"The 11th and 12th holes were definitely the key," said the long-hitting Peck, who also won his afternoon match, 2 and 1, over Don Levin of Elk Grove, Calif.

DeFrancesco, who plays out of Lakewood Country Club, lost the first two holes to Monneyham, who will play for the University of Houston this year.

DeFrancesco, the former Metro Schoolboy champ, pulled even at No. 8 with this second birdie of a front-nine par-5, but Monneyham regained the lead with a bird at nine.

After falling to two down at 12, DeFrancesco again pulled to within one with par on 13.

Clinging to that one-hole lead, Monneyham drove into trees lining the left side of the 18th fairway. DeFrancesco drove into good position on the par-4 hole.

"He's gotta birdie this hole and he knows it," said Monneyham, before hitting a fine shot over some trees and onto the green, 30 feet from the cup.

DeFrancesco hit his approach shot 15 feet from the flag. Both two-putted, giving Monneyham the one-hole victory.

"One more and then bring on (Bob) Clampett," said a jubilant Monneyham as he strode from the final green.

Unfortunately for Monneyham, "one more" turned out to be Steve Owen of Haines City, Fla. Owen ousted Monneyham, 1 up, in the afternoon.

The favour Clampett, out of Carmel, Calif., gained today's quarter-finals with a 6-and-4 afternoon victory over Rod Spittle of Niagara Falls, Ontario.

"My game is closer to where I want it, but not quite there," said the 18-year-old Brigham Young All America after a four-under-par-for-14-holes performance against Spittle.

Jay Sigel of Philadelphia was thumped by Bob Wrenn of Richmond, 5 and 4, in a morning match.

Kalua Makalena of Hawaii eliminated Doug Fischesser of connersville, Ind., a finalist last year, in 19 holes i; n the round-of-16.

Today's quarterfinal pairings: 9 a.m. - Griff Moody, Athens, Ga., va. Peck; Cook vs. Makalena; Scott Hoch, Gary, N.C., vs. Robert Burk, Palm Harbor, Fla; Clampett vs. Owen.