Week 15 of the NFL season played out as expected -- not a single outright upset. Every underdog lost.

The Atlanta Falcons' 24-21 victory over the Tampa Bay Buccaneers on Monday capped a perfect week for the chalk, as all 14 teams that were favored in Las Vegas to win did so. The Falcons didn't cover the six-point spread.

The point spreads on the Los Angeles Rams-Seattle Seahawks game and Los Angeles Chargers-Kansas City Chiefs game closed at pick 'em at most Las Vegas sportsbooks, meaning there were no favorites at the majority of shops.

According to ESPN Stats and Information, favorites had won every game during an NFL week twice previously since the 1970 merger -- Week 9 of the 2005 season and Week 5 of the 2006 season.

Favorites went 11-0 straight-up and 7-2-2 against the spread Sunday, resulting in a costly football week for some Las Vegas sportsbooks. Parlays and teasers -- many of them filled with favorites -- fueled one of the best Sundays of the NFL season for bettors.

"Teasers were particularly bad," Bob Scucci, sportsbook director for Boyd Gaming books, told ESPN.

If a bettor had used a 14-team money-line parlay of all favorites from the closing lines of the Westgate Las Vegas SuperBook, a $100 bet would have won $12,584.40.

William Hill U.S., Nevada's largest sportsbook, said Sunday was one of its worst of the season.

Las Vegas sportsbook operator CG Technology took multiple five-figure parlays that cashed.

"Too many favorites," Jason Simbal, CG Technology's vice president of risk, said. "A guy bet a $50,000 four-teamer: Eagles, Jaguars, Saints, Vikings money line. There was another $20,000 three-teamer: Eagles, Vikings, Saints. There were a couple of them that had the Ravens thrown in there. Here's an $18,000 two-teamer: Eagles, Saints. We needed to get one of those favorites to lose, and we didn't. And it just crushed us."

Jay Kornegay, vice president of race and sports operations for the Westgate SuperBook in Las Vegas, felt fortunate that his losses weren't as bad as they could have been.

"If you would have showed me those scores before the weekend, I would have certainly guessed the worst [Sunday of the season]," Kornegay told ESPN in a text message.

The last-minute, overturned touchdown in New England's 27-24 win over the Pittsburgh Steelers caused six-figure swings in favor of bettors at the Westgate, Caesars Palace and CG Technology sportsbooks.