

Week 8 of the 2025 NFL season was a historic one for betting favorites, as they went 11-2 against the spread to tie the best ATS mark for favorites in any one week since the 1970 AFL/NFL merger. In Week 9, the underdogs got their revenge in a big way.
First, the Carolina Panthers went to Wisconsin and stunned the Green Bay Packers with a 16-13 victory on a last-second field goal. The Panthers were 13.5-point underdogs, per ESPN BET lines, making their outright win the largest for an underdog this season and the largest in the NFL since 2023. It also served as the second-largest upset win in franchise history and the largest since 2000.
Carolina has been an underdog in all of its games this season but is now 6-3 ATS and has won five of those games outright.
The Packers, meanwhile, have now been on the losing end of two of the largest outright upsets of the season. Back in Week 3, the Pack lost to the Cleveland Browns as 7.5-point favorites, which was the largest upset of the season at that point. Sunday's defeat also tied a 2018 loss to the Arizona Cardinals for the largest upset for Green Bay since the 1970 merger.
While the Packers did attract nearly three-quarters of the spread handle for Sunday's contest at ESPN BET, Green Bay -13.5 wasn't an overly popular play across the entire slate. The book said it was only the ninth-most popular bet by total handle across all of its spread offerings.
By contrast, Detroit Lions -9.5 was the most popular play in the Sunday early slate, and garnered over 86% of the tickets at both ESPN BET and BetMGM. That would prove disastrous for the betting public.
The Minnesota Vikingsemerged in Detroit with a 27-24 victory, which would have been the largest upset of the season if not for the Panthers pulling off their straight up win in the same window. It was the Vikings' largest upset win since 2010 and tied for the Lions' largest upset loss in the past 25 years. Dan Campbell also suffered his first ATS loss against Minnesota since taking over as Detroit's head coach.
"Favorites are often popular and after going 11-2 ATS last week bettors are backing the chalk once again in Week 9," BetMGM trading manager Christian Cipollini said in an email before Sunday's action. "The sportsbook will be looking for a few underdogs to win outright on Sunday."
As with most large favorites, the Packers' and Lions' money lines were popular parlay selections, ranking first and fifth respectively at ESPN BET. The Indianapolis Colts, who also lost Sunday, were the fourth-most popular money-line parlay selection.
Overall, through the Sunday late afternoon games, underdogs went 8-4 ATS and 5-7 outright in Week 9.