It will be Gill FitzHugh of Army Navy against Barry McCarthy for the District Amateur Championship at Chantilly today in a 36-hole showdown starting at 9 a.m.

Both men had to play fine golf to gain the finals. FitzHugh, who admitted he was "playing as solid as I can," beat home-club favorite Tony DeLuca, 2 and 1. McCarthy birdied the 18th hole to turn back stubborn Tom Loveless, of Argyle, one up.

"Tom could have blown me away if he hadn't been putting so poorly," said McCarthy, a recent Virginia Tech graduate. In the morning, McCarthy turned back Chuck Hardie of Argyle, on the 19th hole, while FitzHugh disposed of Ray Anderson, of Chantilly, 4 and 3. DeLuca beat clubmate A. C. Everett Jr., 3 and 2, to gain the semifinal and Loveless defeated David Stewart, Montgomery Village 4 and 3. s

FitzHugh, medalist in this tournament, has had a remarkable run. Counting his five-under-par 67 on Thursday, he has been 14 under par. Yesterday, FitzHugh, a former champion (1973) who likes to whistle when he plays, was three under par in his morning match against Anderson and three under against DeLuca.

FitzHugh was one up after the first nine with DeLuca, thanks to a birdie on the par-5 sixth hole. DeLuca squared it when he parred the 10th after FitzHugh missed a two-foot putt.

They halved the next six holes until the 17th. DeLuca, who made second team all-America this year playing for the University of Florida, hit his drive out of bounds. FitzHugh parred the hole and that was it.

McCarthy and Loveless were even after the first nine. The advantage seesawed back and forth until the 18th when McCarthy made a 15-foot three-footer for the birdie that would have sent the match into extra holes.

In his morning match against Hardie, McCarthy birdied the 17th to tie the match and then won it on the first extra hole with a par to Hardie's bogey.