Defending champion Tom McKnight of Galax, who went the entire two-round day without a bogey; 20-year-old Miller Baber of Roanoke, who kept his poise despite a couple of disastrous second-match putts, and medalist J.P. Leigh of Portsmouth advanced to the quarterfinals of the Virginia State Amateur golf tournament yesterday at the Country Club of Fairfax.

McKnight, 30, seeking to become the first repeat winner since 1975, was three under par in both his matches. He beat Jimmy Merriman of Bassett, 5 and 4, and Gary Strickfaden of Roanoke, 3 and 1.

Baber ousted 1980 champion Mark Lawrence of Richmond, 2 up, in the second round after a 2-and-1 decision over Chuck Tickle of Pulaski.

Leigh, 37, one of six former pros who made it past the first round, had to go 18 holes for 1-up decisions over Tom Dozier of Portsmouth and David Newland of Annandale.

In today's quarterfinals, Leigh will face Moss Beecroft of Newport News, a 2-and-1 winner over Fairfax's Hubert Botts and a 4-and-3 winner over Chantilly's Robert Harwick; Baber will play Mike Pratt of Richmond, 4 and 3 over both Chris Schmitz of Springfield and Michael Leahey of Norfolk; McKnight will meet Bill Jahn of Norfolk, who ousted Newport News' Wayne Jackson, 1 up, and Danville's Bill Harris, 3 and 2, and Sam Stein of Richmond will face Chuck Wemp of Lynchburg. Stein earned 2-and-1 decisions against Salem's Bille Willette and Reston's Tim Vigotsky. Wemp won both his matches, 2 and 1, against Waynesboro's Mark Teachey and Lake Monticello's Michael Moraghan.