Robert (Boo) Sawyer of Washington, knocked out Ken Johnson of Philadelphia with 1:50 gone in the first round of the feature bout before 1,150 fight fans at the Washington Coliseum last night.

Sawyer (4-1), the 1979-80 DCAAU Golden Gloves champion, didn't even work up a sweat in the welterweight bout. From the opening bell it was apparent that Johnson (7-5) was in over his head. Sawyer's lightning jab kept Johnson from landing a solid blow. Sawyer backed Johnson into a corner and caught him with a solid left hook and sent him to the canvas.

In the preliminary bouts Dexter Mason decisioned Paul Grant in a 160-pound contest; George Burton registered a TKO over Anthony Williams in a 147-pound fight; Joe Robinson scored a second-round TKO over Ocie Harper at 140 pounds; Lloyd Taylor knocked out Billy Hunt at 1:51 of the second round in a 147-pound bout; Ronnie Dominique stopped Bob Murphy in the second round of a 160-pound match; Robert McConnell (175 pounds) decisioned Ed Harris; Halimah Saalakhan decisioned Clifton Haywood at 135, and Mike Passero knocked out Ira Robinson in the second round of their 140-pound bout