BALTIMORE — Chris Sale struck out 13 to become the first AL pitcher in 18 years to reach the 300 mark, and the Boston Red Sox moved to the brink of clinching a playoff berth by beating the Baltimore Orioles 9-0 on Wednesday night.

Sale (17-7) reached the milestone on his last pitch, a called third strike against Ryan Flaherty to end the eighth inning. The last AL pitcher to fan 300 batters in a season was Boston’s Pedro Martinez in 1999, when he set a club record with 313.

Mookie Betts and Deven Marrero homered for the Red Sox, who reduced their magic number for reaching the postseason to one. If the Angels lost to Cleveland later Wednesday night, Boston would be assured no worse than a wild-card spot in the AL playoffs.

The Red Sox, of course, would prefer to enter as AL East champions. They hold a three-game lead over the second-place Yankees with 10 games left.

Boston jumped to a 6-0 lead in the fifth and rolled to its 11th win in 14 games.