Peter Hiskey birded three of the final six holes yesterday to win a semi-final match with Jim Bryan and reach Sunday's championship round of the 28th Annual Bubby Worsham Memorial junior invitation golf tournament at Bethesda Country Club.

Hiskey's opponent in the 1 p.m. final willbe Larry Rentz, a semifinal round winner over Alan Chippendale.

After winning a quarterfinal match over J. B. Whaley of Wilmington, Del., 2 And 1, yesterday morning, Hiskey started off by winning the first three holes against Bryan. Bryan, an upcoming junior at Bowling Green (Ohio) State University who lives in Latrobe, Pa., missed putts of seven and three feet for pars on the second and third.

Bryan came back to win three of the next six holes while halving the others. But then Hiskey, who is entering his senior year at Northwestern High School, took over.

On the 379-yard, par-4 10th, he reached the green with his second shot and holed an 18-footer for a birdie to go up by one.

After taking the 11th after Bryan's bogey 6, Hiskey sank a birdie putt on No. 12 to go 3 up.

Bryan then missed a 3 1/2-foot putt for par on the par-3 13th to go deeper in the hole. It appeared that Bryan might get a reprieve on No. 14 when Hiskey's tee shot landed under a tree 15 feet into the right rough.

But Hiskey squeezed his lanky body under a low-hanging branch and, using a seven-iron skimmed second shot out of the woods that landed 22 feet from the cup. Hiskey watched Bryan barely miss an 18-footer for a birdie, then two-putted himself as both players settled for a par 4.

On the decisive 15th, Bryan's 17-foot putt for a birdie 3 rolled over the cup. Hiskey left a wedge shot five feet from the hole on his second stroke and then calmly sank it for the birdie and the match, 5 and 3.

Rentz earned a spot in the championship round for the second straight year - having lost to Joe Walter on the 19th hole last year - with a 3-and-2 decision over Chippendale.

Rentz won the third, eighth and ninth holes to go 3 up after the first nine. Chippendale, a native of Montreal who is a teammate of Bryan on the Bowling Green golf squad, missed an eight-foot putt for par on the third and bogeyed the par-4 eighth. On the ninth hole, he missed a three-foot par putt.

Rentz who plays out of Crofton and will be a sophomore at the University of Florida, picked up two more holes when he birdied the par-5 11th and Chippendale bogeyed the par 4 12th.

Chippendale won the 13th, the pair halved the next hole and the Canadian won No. 15 after Rentz lipped the hole on a putt for par that would have meant a half and won the match for Rentz.

On No. 16, Chippendale's six-foot putt for birdie-3 stopped three inches short and Rentz sank a three-footer for par and the match.

In the final of the second flight, Vern Caswell of Brooke Manor defeated Webb Heintzelmannof Washingtonian on the 19th hole. Cobby Webb of Greencastle beat Paul Hiskey, University of Maryland course, 4 and 3, for the 13-under title. In the 14-15 championship, Todd Anderson of Wilmington, Del., knocked off Wes Bickham of Crofton, 4 and 2.