Ken Griffey hit a grand slam home run in the first inning and Don Baylor followed with another homer to lead the New York Yankees to an 11-3 victory and a sweep of a twinight doubleheader with the Toronto Blue Jays last night in Yankee Stadium.

Oscar Gamble drove in three runs, two with his seventh homer, and Dave Winfield and Butch Wynegar each had two RBI as the Yankees won the opener, 8-3. Ron Guidry pitched an eight-hitter.

Bob Shirley (4-6), who had pitched only five innings in three appearances since July 1, held the Blue Jays to one run and six hits over the first six innings of the second game. He started the game with a 2.86 ERA in Yankee Stadium and a 9.10 ERA on the road. Toronto lost its sixth straight; until this streak, it was the only team in the majors that hadn't lost more than three games in a row.

Toronto scored a run in the first, but rookie Matt Williams, making his second major-league appearance, failed to retire a batter in the bottom of the inning. Singles by Willie Randolph and Graig Nettles and a walk to Winfield loaded the bases. Griffey hit his sixth homer of the season and second career grand slam far into the bleachers in right center, and Baylor followed with his 15th homer to knock out Williams (1-1).

Guidry (13-7) walked three and struck out three in pitching his 12th complete game of the season.