Matt Williams survived three home runs in five innings to win his major-league debut and Rance Mullinks drove in four runs as Toronto trounced the visiting New York Yankees, 13-6, and swept a twinight doubleheader before 45,102 last night, the largest crowd in the Blue Jays' seven-year history.

The Blue Jays won the first game, 10-9, when Dave Collins singled home Garth Iorg from second base with one out in the 10th. Toronto, which trailed, 6-2, after 2 1/2 innings, tied the score, 9-9, on Ernie Whitt's bases-loaded sacrifice fly off New York relief ace Rich Gossage in the ninth.

It was Toronto's eighth extra-inning victory of the year and 11th in a row over two seasons.

The Yankees, who have lost five of their last six games and are fifth in the tight American League East, left the bases loaded twice in the nightcap after wasting five home runs in the first game. Their pitchers were pounded for 28 hits in the doubleheader. In addition, shortstop Roy Smalley committed a costly two-run error in the opener and right fielder Oscar Gamble dropped a line drive that led to a pair of unearned runs in the nightcap.

Roy Lee Jackson (8-1) won the opener for his eighth straight triumph, a club record.