Through the first five games, the World Series averaged 11.6 million viewers, the Nielsen company said. That puts it on pace to be the least-watched Fall Classic ever, although ratings tend to pick up when a series reaches a sixth or deciding seventh game.
The Nationals beat the Astros 7-2 on Tuesday night to force a Game 7 in Houston on Wednesday.
From an audience perspective, the Series was really hurt Sunday night, when 18.3 million people watched an NFL game between the Green Bay Packers and Kansas City Chiefs compared to the 11.4 million who tuned in to baseball at the same time. That's the widest viewership margin an NFL game has ever had over a World Series game at least since Nielsen began keeping more precise records in 1987.
The Associated Press contributed to this report.