... in sports, two teams from the same conference/division/league play each other in what analysts describe as the “de facto” championship game.

For example, a few years ago in the NFL, the Indianapolis Colts and New England Patriots faced off in the AFC Championship. Experts coined it the “de facto” Super Bowl, saying that either team would easily handle whatever foe the NFC put forth.

In college basketball, it’s been said about semifinal games between Kansas and North Carolina. In MLB, the ALCS has often been called the de facto World Series due to the superiority of the American League.

Bleacher Report - College Football