They repeated as American League West champions and swept the Cleveland Indians in the ALDS to advance to the ALCS, where they lost in five games to the Boston Red Sox.

Additionally, ace Justin Verlander finished as runner-up for the American League Cy Young Award for the second time in three years.

The Houston Astros entered the 2018 Major League Baseball season as defending World Series champions after defeating the Los Angeles Dodgers in seven games.

[7] On January 23, 2018, first baseman Jon Singleton and pitcher Dean Deetz were suspended after testing positive for substances violating MLB's drug policy.

[8] Justin Verlander was the Opening Day starting pitcher for Houston at Globe Life Park in Arlington, versus Cole Hamels of the Texas Rangers.

He struck out Shohei Ohtani in the top of the ninth inning for his 2,500th career strikeout, becoming the 33rd pitcher in Major League history to cross that threshold.

On September 26, 2018, Houston won the American League West division title after the Oakland Athletics were defeated by the Seattle Mariners, following a 4–1 win against the Toronto Blue Jays.