NFL gamblers went on a bit of a heater in NFL Week 9. (Ethan Miller/Getty Images)

Nevada’s sportsbooks had a record-breaking month of September, winning an all-time high of $56.3 million off $571 million worth of bets (the latter amount also setting a new mark). But things have taken a turn in recent weeks, and on Sunday, the books were devastated by a perfect storm of highly bet NFL teams covering the spread and winning outright with ease.

All told, Nevada’s sportsbooks lost between $7 million and $10 million Sunday, industry sources told ESPN’s David Purdum.

Bettors' winning ways started with the 1 p.m. games, when the heavily bet Vikings, Chiefs, Steelers and Bears all won and covered with relative ease, outpacing the point spread in their games by an average of 12.3 points.

According to pre-kickoff numbers supplied by William Hill US before kickoff of the 1 p.m. Eastern games Sunday, 86 percent of the spread tickets and 87 percent of the total money was on Minnesota, which defeated Detroit, 24-9, as a 4.5-point favorite; 91 percent of the tickets and 88 percent of the money was on Kansas City, which defeated Cleveland, 37-21, as an eight-point favorite; 76 percent of the tickets and 61 percent of the money was on Pittsburgh, which defeated Baltimore, 23-16, as a 1.5-point underdog; and 65 percent of the tickets and 59 percent of the money was on Chicago, which defeated Buffalo, 41-9, as a 10-point favorite.

You can throw in the Panthers, who covered easily as a six-point favorite against Tampa Bay; William Hill said Carolina received 71 percent of the tickets and 71 percent of the money.

“The public just nailed it,” Boyd Gaming sportsbook director Bob Scucci told Purdum. “They had the big favorites — Bears, Chiefs, Panthers and Vikings — as well as the short 'dogs, Texans and Steelers. And a lot of the overs.

“By the time we got to the two biggest games — Packers-Patriots and Rams-Saints — there were so many parlays alive that we were going to lose no matter what.”

Jay Rood, vice president of race and sports for MGM, gave the day a one-word description to Purdum: “Disaster.”

According to Sports Insights, NFL teams that received a majority of the spread bets went a perfect 11-0 on Sunday, both against the spread and straight up. Only two final scores finished within four points of the point spread: The Texans' 19-17 win over the Broncos as one-point underdogs and the Dolphins' 13-6 win over the Jets as three-point favorites.

It was the third straight NFL Sunday in which bettors put up a strong fight in Vegas. In Week 7, the Chiefs, Patriots and Bears all won as big favorites, leading to “the first real bad Sunday” of the NFL season, Rood told Purdum. In Week 8, the heavily bet Saints, Redskins and Bears all covered, securing “not a bloodbath but a solid loser” for the South Point sportsbook, director Tim Fitzgerald told Purdum.

The three-week run of success for bettors seems likely to be fleeting, if history is any indication: Vegas sportsbooks haven’t had a losing month since July 2013.

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