The list of potential World Series winners dwindled to five after Atlanta, Houston and the Los Angeles Dodgers won their respective division series Thursday.
The trio of teams will be joined by either the New York Yankees or Tampa Bay Rays, who face off in ALDS Game 5 Friday.
While the Yankees and Rays have shown they are worthy title contenders this season, they will be at a significant disadvantage going into the ALCS against Houston.
Since the Astros clinched Thursday, they have two days to rest their pitching staff, while the Yankees and Rays only have one day to rest up and align their rotations.