NEW ORLEANS — The moment Garrett Hartley's foot drove through the ball, the Louisiana Superdome crowd erupted and Saints owner Tom Benson raised his arms in triumph.

The presumption was that these Saints, in this magical season, were going to pull out another win in the clutch.

Not so fast.

Hartley's 37-yarder hooked to the left, and those who'd allowed themselves to celebrate prematurely were sent home soon after in stunned silence.

Carnell Williams rushed for 129 yards and a score, and Connor Barth kicked a 47-yard field goal in overtime, lifting Tampa Bay to a 20-17 upset yesterday that, for the time being, prevented New Orleans from securing home field throughout the NFC playoffs.

Even in what will go down as the best regular season in Saints history, a franchise long known more for its stumbles than success found a way to make history with a loss. According to STATS LLC, the result marked the first time a 13-win team lost to a team that came in with only two victories.

"It's hard to explain," Saints quarterback Drew Brees said. "We started off fast, then after that there was a big lull."

New Orleans (13-2) has lost two straight — both at home — starting with a 24-17 setback to Dallas.

If Minnesota wins its final two games, starting tonight in Chicago, the Saints will have to win in Carolina next Sunday to secure the franchise's first No. 1 playoff seeding.

New Orleans sped out to a 17-0 lead on its first three possessions against Tampa Bay (3-12). But Williams scored on a 23-yard run in the fourth and Micheal Spurlock's 77-yard punt return tied it at 17 with 2:25 left.

After Hartley's miss with 9 seconds left, Tampa Bay won the coin toss to open overtime and scored soon after.