Take Las Vegas and the NFL, add the world's hottest pop star, a love story that has social media spinning like a slot machine, two superb teams and you get what might be a landmark Super Bowl cementing Sin City's status as a global sports hub.

Already the United States' biggest sporting party, Las Vegas is promising a Super Bowl supernova around the Kansas City Chiefs and San Francisco 49ers showdown on Sunday.

The reigning champions Chiefs, making a fourth Super Bowl appearance in five seasons, take on the 49ers, who with a win will bring home a sixth Lombardi trophy and join the Pittsburgh Steelers and New England Patriots for the most all-time titles.