Sportsbooks in Las Vegas took a big hit on the first Sunday of the NFL season. A number of teams favored to win that were popular with bettors covered the points spread, leaving the house in trouble, ESPN reported Monday.

"I don't remember a worse opening Sunday," said Jay Kornegay, chief of the Westgate SuperBook, to ESPN. A number of other books in Las Vegas reported a bad opening day to ESPN, including William Hill, the MGM, Caesars, CG Technology, Stratosphere and Station Casinos. Covering the spread means a team won or lost by a certain amount of points either given or taken away by books to gamblers placing bets on the team. 

Opening Sunday is usually a big win for books, but on a day in which favorites went 9-4 against the spread, Las Vegas struggled. A number of key games worked against Vegas. The Green Bay Packers, a common favorite for fans placing bets, covered a 6.5-point spread against the Chicago Bears in a 31-23 victory. The Miami Dolphins were a popular pick as 4-point favorites over the Washington Redskins and covered with a 17-10 win.

"There are definitely some long lines cashing tickets," Chuck Esposito of Station Casinos told ESPN Sunday.

Last year's opening day, in which underdogs covered in 10 of 13 games, was dramatically different. Las Vegas won big as popular favorites betted on by the majority of the public faltered. 

“This was the best opening day we’ve ever had here,” said Golden Nugget sports book director Tony Miller to Sporting News last year. "Just about every game we needed came through for us."

Las Vegas has been on an NFL losing streak recently. Prior to this year's Week 1, the last competitive NFL football was played during February's Super Bowl matchup between the Seattle Seahawks and the New England Patriots. The Super Bowl is a massive day for gamblers, and is typically a boon for sportsbooks.

But a last-second, game-saving interception by Patriots cornerback Malcolm Butler left Las Vegas reeling because in the process it sealed both New England covering the spread and the total points scored going over 47.5. “That was our one losing scenario,” said Nick Bogdanovich, William Hill sports books’ director of trading, to the Las Vegas Sun after the Super Bowl. 

The house likely won't stay down for long. Nevada sportsbooks won a record $113.7 million on football last year, according to ESPN.