John Haddock of Penderbrook and Tom Splaine of Montgomery Village won their matches yesterday to advance to the final of the Marvin (Bubby) Worsham Memorial Junior Invitational golf tournament at Bethesda Country Club.

In the first of the semifinals, the 17-year-old Haddock, a 125-pound senior-to-be at Annandale High School, upset Webb Heintzelman of the University of South Carolina and Washington Country Club, 4 and 2.

Haddock, the reigning Virginia high school AAA champion, was continually outdriven by Heintzelman, but compensated with deft play with his short irons and putter.

Beginning at the sixth hole, Haddock had 10 consecutive pars, a consistency that wore down former Worsham champ Heintzelman, who conceded after sending a shot into the brambles at 16.

"My strategy was to make all pars. Although I only hit it fair off the tees, I chipped and putted like a professional. Those chips and putts saved me," Haddock said.

In the other semifinal, Splaine shattered hopes of an all-Annandale High final by besting David Newland of Penderbrook, 2 up.

Splaine enjoyed a three-stroke lead after 15 holes, but nearly played himself into sudden death by dropping 16 and 17 to Newland, a 1980 Annandale graduate. ywhen he put his second shot onthe par-4 18th 12 feet from the cup, the tall, blond Gaithersburg High senior had assured his progression to today's 10 a.m. title match.

In other matches yesterday, Jim Estes of the host club won the consolation title, while Peter Nadanyi of International won the 14-16 category. Mike Watson of Lakewood won the 13-and-under bracket.