The biggest factor in keeping viewers tuned in is the competitiveness of the game. A rout is generally bad news, although recent history is on Fox's side. After a run of lackluster Super Bowl games, this decade has seen some good ones. The playoffs leading up the Super Bowl, capped by the Giants' overtime victory over Green Bay, also bode well.
The best thing for Fox would be a close game with the Giants leading, but the Patriots still with a chance at the end.
The element of history might keep viewers tuned in even if the Patriots are blowing out the Giants, although the big victory margins the team was racking up early in the year have diminished.
''If New England blows out the Giants, this may be one time when ratings late in the game will not decline,'' said Steve Sternberg, ratings expert for the ad-buying firm Magna Global. ''The only thing that might prevent near-record ratings is if the Giants blow out the Patriots. But even that might keep viewers tuned in.''
Other, esoteric factors might help, too. Bad weather across the country could keep people in front of their TVs, in case they were tempted to do something else.
The Hollywood writers strike might leave viewers a little more starved than usual for something good to watch, Adgate said.
The Super Bowl is the most popular television event of the year. This year's game will almost certainly fail to match the most popular television event of all time, the 1983 finale of the TV series ''M-A-S-H,'' which drew an estimated 125 million people.
Even if this week's game cracks the viewership record, it is still not likely to earn the best Super Bowl rating — because of factors out of the game's control. The ratings record of 49.1 — meaning just under half of the nation's TV sets were tuned in to the game — was set for the 1982 game between San Francisco and Cincinnati. The simple explosion in the number of TV networks available for people to watch makes that a hard number to approach.
The biggest winners may be the game's advertisers, even as the cost for a 30-second ad reaches a record $2.7 million.
''It could be construed as a bargain,'' Adgate said. ''Outside of 'American Idol,' there's no real top-rated show that advertisers can bank on right now. Even the Oscars are in a state of flux, and that's always been called the Super Bowl for women.''