A two-out top-of-the-ninth home run by veteran rightfielder Rick Monday broke a 1-1 deadlock, giving the Los Angeles Dodgers a 2-1 victory over the Montreal Expos and the National League pennant yesterday afternoon in wintery Montreal.

The near freezing temperatures didn't seem to faze the Dodgers, least of all rookie ace Fernando Valenzuela, who held Montreal to three hits in eight and two-third innings and drove in a run on a groundout. Valenzuela fanned six Expos with an accurate screwball and allowed no unintentional walks until the ninth.

Ray Burris, who beat Valenzuela in the third contest of the series, kept the Dodgers off the board for much of the game. The six-foot five-inch allowed five hits and one walk in eight innings.

As a pitching duel developed, the game turned more on strategy and small breaks than on the long ball. Following his first-inning double, Expo Tim Raines reached third on a fielder's choice and scored on a double play.

In the top of the fifth Rick Monday singled and went to third playing hit-and-run on Pedro Guerrero's single. Guerrero took second on a wild pitch, while Monday held. With the force-play removed, an inning-ending double play on Valenzuela's ground ball was impossible, and Monday raced home.

Burris gave up several long flyouts in the seventh, was taken out for a pinch-hitter, and was relieved by Steve Rogers in the ninth. Rogers, pitching in relief for only the third time in his career, became the losing pitcher as Monday stroked a three-and-one pitch over the centerfield wall.

Though Expo fans were disapointed, nostalgia buffs should be pleased as the Dodgers will be facing the Yankees in the World Series for the eleventh time. The Series begins tonight at Yankee Stadium.