Blake Snell baffled batters for eight innings but the Los Angeles Dodgers nearly squandered his heroic effort before taking a 2-1 victory at Milwaukee on Monday in their Major League Baseball playoff series opener.

Snell surrendered only one hit over eight shutout innings. The 32-year-old American left-hander delivered a playoff career high 10 strikeouts with no walks and faced the minimum 24 batters, retiring the last 17 he faced.

"If you can 'locate' the fastball, it sets everything else up," Snell said.

But after Japanese closer Roki Saski surrendered a run and loaded the bases in the ninth, it took reliever Blake Treinen striking out Brice Turang with the bases loaded to preserve a tension-packed victory for the defending World Series champions.

"I trust Roki. I trust Blake. You've just got to attack the zone better," Snell said. "They had a lot of walks there, had one hit, but those guys are going to figure it out. They're really good."

Freddie Freeman's solo homer to right field in the sixth inning off Brewers reliever Chad Patrick gave the Dodgers a 1-0 lead and Milwaukee closer Abner Uribe's bases-loaded walk to Mookie Betts in the ninth gave the Dodgers the deciding run.

The Dodgers seized a 1-0 lead in the best-of-seven National League Championship Series, which continues Tuesday at Milwaukee.

The NL champion will face the American League champion, either the Seattle Mariners or Toronto Blue Jays, in the World Series, which begins on October 24.

Seattle's Julio Rodriguez and Jorge Polanco each smashed three-run home runs to power the Mariners over host Toronto 10-3 earlier Monday for a 2-0 lead in the NLCS with game three on Wednesday in Seattle.

The Dodgers are trying to become the first team to repeat as World Series champion since the New York Yankees won the 1998-2000 crowns.

The Brewers, who led MLB with 97 wins this season, reached their only World Series in 1982, losing to St. Louis in seven games.

Meanwhile, the Mariners return to Seattle needing two more wins to reach their first World Series.

"I expect a lot of noise from the fans," Polanco said. "They will bring a lot of energy for us. We'll just keep competing."

The Blue Jays, in their first ALCS since 2016, won their only World Series appearances in 1992 and 1993. (AFP)