After Baltimore lefty Mike Flanagan became the major leagues' first 20-game winner today, his pitching coach, Ray Miller, poured champagne over Flanagan's head in celebration. Flanagan quickly put things in proper perspective.

"I haven't played in a World Series," Flanagan said. "A lot of guys here haven't. That's what's really important to us."

Today's overtime chores on Labor Day carried the Orioles closer to that goal. Flanagan's 5-1 breeze followed an 11-inning, 2-1 triumph decided by Eddie Murray's bases-loaded single. That gave Baltimore its seventh sweep in 10 doubleheaders, a 90-victory season, an 8 1/2 game lead over Milwaukee and an 11-game edge over Boston.

Flanagan was held for game two so that his fast ball would be more effective in the lengthening shadows. It proved so, as he scattered seven hits, fanned six, walked three and enjoyed an easy time after the Orioles staked him to a 4-0 lead in the second inning.

Toronto started Dave Lemanczyk was pummeled in that frame by Pat Kelly's sixth homer, doubles by Doug Decinces, Billy Smith and Dave Skaggs, and a single by Al Bumbry.

"I had a few butterflies tonight" Flanagan said. "They had me wait around and that probably relaxed me more. The fans were a little dead at the start of the game and that relaxed me, too. Then getting those four runs early took a lot of the pressure off.

"I was disappointed last year when I didn't get it, so I have to be satisfied now. The only thing is, the guys were telling me, particularly (Jim) Palmer, that once you win 20, they expect it all the time."

The Orioles have had at least one 20-game winner every year since 1968 and Palmer has reached the coveted figure eight times. This was the first such experience for Flanagan, who finished 19-15 last year after dropping a 5-4 decision in his last start at Detroit.

"It's nice to be put on the board and make them change that trivia question," Flanagan said. "It's remarkable that Jim made it eight times. He's helped me a lot. He's been through it all. You get a lot of help on this club. The pitching staff is tremendously close, and we don't have a lot of egos here.

"It seems that days when I'm a little off, we get five or six runs. And when they don't hit much I have a little extra stuff. I just hope it keeps going that way right through the Series."

Flanagan's record is now 20-7, he has won six in a row and 10 of his last 11. Meanwhile, the Birds have beaten the Blue Jayes 14 straight, nine times this season, and that is a big turnabout from early 1978, when Flanagan was the loser in a 24-10 game that ignited a four-game Blue Jay sweep in Toronto.

Today the Blue Jays were reaching the 94-defeat figure and producing some more heartbreak for left-hander Tom Underwood, who deserved a 1-0 shutout victory in the opener but left instead after 10 innings with his 6-16 record unchanged. He then watched reliever Tom Buskey throw it all away in the 11th.

After pinch-hit expert Kelly, who has gone 11 for 21, greeted Buskey with a single to right, Rich Dauer bunted back to Buskey. With a force play in sight, Buskey heaved the ball into center field, placing runners on second and third. Ken Singleton was intentionally walked, then Murray sent a long fly that one-hopped off the left field fence.

The beneficiary was Tippy Martinez, who boosted his record to 9-2 with one perfect inning in relief of Oriole starter Steve Stone. Rick Cerona's third-inning homer was the only run off Stone, who is 7-1 with a 1.851 earned-run average here, compared with 2-6 and 6.37 figures on the road.

Baltimore tied in the same inning, Dauer driving a two-out double past third baseman Roy Howell and Singleton scoring him with a tainted triple.

Singleton stroked a blooper to right that seemed catchable with a little extra effort. Former Oriole shortstop Bob Bailor started in late, stopped to play it safe and leaped in vain as the ball took a bad hop over his head.