The Red Sox magic number remained stuck at 1 on Friday after a 3-2 loss to the Astros at Fenway Park.
The Astros jumped out to a 3-0 lead that the Red Sox could not overcome.
Now the Red Sox must either win one of their two remaining games or have the Yankees lose one of the two remaining games against the Yankees to clinch the AL East.
If the Sox lose both and the Yankees win both, the teams would be tied atop the division after 162 games. They would then meet in a one-game playoff in New York on Monday to decide to wins the division and who claims the wild card.