sentences:  The NFL instated a new "flex-scheduling" policy in which the NFL could choose a game to be aired in primetime on NBC based on the team's current performance and record.Previously, Sunday night NFL games were televised by ESPN, from 1987–2005, and TNT, from 1990–1997.Starting with the 2006 NFL season, NBC was awarded the rights to air Sunday night primetime American football games, as well as the rights to air two games of the NFL playoffs.