Medalist Gill FitzHugh, playing the best golf of his career, gained the quarterfinal of the District Amateur championship at Chantilly yesterday with victories over Jim Krouse and Gary Clontz.

FitzHugh will play Ray Anderson of Chantilly in his first match today while A.C. Everett, another host-club amateur, faces clubmate Tony DeLuca, cofavorite with FitzHugh. However, both are in the same bracket.

In the upper half of the draw, Barry McCarthy of Bell Haven meets Chuck Hardie of Argyle, and David Stewart, Montgomery Village, plays Tom Loveless of Argyle.

Robert Black, the detending champion, was ousted in a morning match on the 23rd hole by Jeff Cherner of Indian Spring. Black's drive on the fifth extra hole went under a fence and he lost to a par. But Cherner, who works at night and had been without sleep for most of the last two days, tired in the afternoon, losing to McCarthy, 6 and 5.

McCarthy has had the easiest time in the tournament. He disposed of his morning opponent, Hall Dillion of Montgomery Village, 7 and 5. McCarthy lost only one hold all day.

FitzHugh, who represents Army Navy, won this title in 1973, beating his brother, Woody, now on the protour. FitzHugh recently won the Northern Virginia Amateur title and was a finalist in the Virginia State.

He was even after nine holes in his afternoon match and won the 10th with a par and the 12th with a 15-foot birdie putt. He and Clontz halved the next four holes. But Clontz sank a 20-foot putt for a birdie on the 17th, only to have FitzHugh roll one in on top from 10 feet to close the match.

DeLuca and Burke were even through the 12th hole, then DeLuca chipped to within inches of the cup at 13 for a birdie. He went 2 up at the 14th with another birdie when he put an eight-iron shot two feet from the pin. The players then halved in and DeLuca won on the 17th.