Wayne DeFrancesco of McLean, Va. and Columbia Country Clubbers Marty West and Henri deLozier of Chevy Chase, Md., posted victories in yesterday's third round of the U.S. Amateur golf championship.

DeLozier beat Tim Burns of Clarks Summit, Pa., 4 and 3. The match ended with a slight controversy on the 15th hole.

West turned back Warren Choate of Williamsport, Pa., 4 and 2 DeFrancesco won every hole on the back nine and blitzed Lee Martinson of Ridgewood, N.J. 6 and 5.

Steve Fellinger of Niagara Falls, Ontario, who shared the spring Belle Haven Four-Ball championship while playing for the University of Maryland, was bounced by Lee Davis of Los Angeles, 2 up.

The strange ending to the deLozier match occurred minutes after Burns had pulled to 3 down with par on the 14th hole.

On the par-4 15th, both were just off the green in two shots. Burns, thinking he was away, made a fine chio stiff to the pin for what looked a sure par.

DeLozier thought he was well away and should have chipped first. The former Maryland Open champ hit his third shot 30 feet beyond the hole, then called on a U.S. Golf Association officials to step off the distances to see who had been away.

The USGA officials paced it off and determined that deLozier was away and should have hit first.

As was his option, deLozier had 17-year-old Burns replace his ball and replay the chip shot. After Burns replaced the ball and addressed the shot, the ball moved. Burns called for a ruling on that and was assessed a penalty stroke. The flustered Burns then stubbed his chip shot and dejectedly conceded the match.

"I had to do it," said deLozier of his right of recall. Burns, though shocked, said, "It's not your fault," to deLozier. "It hurts," Burns said later. "I felt I was back in the match. I would have been two down with three to go."

DeLozier had gotten into winning position by playing three-under-par golf from the second hole through the 13th.

West kept mistakes to a minimum and dispatched big Choate, who qualified for the 1977 and '78 U.S. opens.

The key was the par-5 12th. Choate had a chance to pull within one but was too aggressive with his eight-foot downhill birdie attempt. The putt slid three feet by the cup. Choate missed coming back and was 3 down. They halved the next three holes and West won on the 16th with par 5 to Choate's bogey.

"It's my kind of golf course," said West. "You've got to drive it straight and hit a lot of medium irons. And you've got to use your head."

DeFrancesco, who feels his swing is as mechanically sound as any here, won with ease when Martinson lost his poise on the back nine.

"The tournament starts now," said DeFrancesco, LSU junior who reached this point two years ago in this tournament.

The turning point against Martinson, who eliminated 1974 champ John Grace on Wednesday, was the 10th hole. DeFrancesco went 3 up with an "up and down" par from a greenside trap and Martinson took three from the edge.

DeFrancesco, the District of Columbia Amateur titlist, won the next two holes with par and applied th coup de grace with a 10-foot birdie on the toughes hole on the course, the long par-4 13th. Martinson completely lost his cool in the face of grim shotmaker DeFrancesco.

"I used to do that," said DeFrancesco. "It doesn't do anything but make you lose faster."

In other top matches, Jay Sigel of Philadelphie edged Pennsylvania Amateur champ Frank Fuhrer of Pittsburgh, 1 up. Another favorite, Bob Clampett of Carmel, beat James Johnson of Roanoke, Texas, 3 and 2.

Wayne Player, son of PGA star Gary Player, was eliminated by David Lane of Chelmsford, Mass., 3 and 2. Doug Fischesser of Connersville, Ind., finalist last year, sidelined Jefferson Morgan of Miledgeville, Ga., 4 and 2.