NEW ORLEANS - By refusing to give up on the season, Carnell Williams and the Tampa Bay Buccaneers have prolonged the New Orleans Saints' quest for home-field advantage throughout the playoffs.

Williams rushed for 129 yards and a score, and Connor Barth kicked a 47-yard field goal in overtime, delivering a stunning 20-17 victory over the Saints yesterday.

New Orleans was heavily favored and could have guaranteed itself home games throughout the NFC playoffs with a win, but instead dropped a second straight game at home after opening the season 13-0.

"Listen, I've said this before. In our league, it's crisis or carnival," Saints coach Sean Payton said. "The stuff in the middle doesn't sell. Our players understand that. Now, you hit some adversity. We've got to get ready to play a team that's playing well in Carolina."

Williams had a 23-yard TD run in the fourth quarter, and Michael Spurlock's 77-yard punt return tied it, completing a comeback from 17 points down in the first half.

The Saints had a chance to win in the final seconds of regulation, but Garrett Hartley missed a 37-yard field goal. Tampa Bay then won the coin toss to open overtime and scored soon after.

Although the Saints jumped out to a 17-0 lead and appeared en route to an easy win, the Buccaneers kept playing hard and were the better team in the second half.

Spurlock's game-tying score came after the Bucs had squandered two other scoring chances, once on Tracy Porter's interception in the end zone and once on a failed fourth-and-short from the New Orleans 19-yard line.

New Orleans, shut out throughout the second half, finally drove into field-goal range in the final seconds, but Hartley hooked his kick badly to the left.

Tampa Bay's defense continued to show improvement since coach Raheem Morris took charge of the group after New Orleans' 38-7 win at Tampa Bay six weeks ago.

Drew Brees was held to 258 yards passing and one touchdown. The Saints rushed for 124 yards, but gained only 28 yards on the ground in the second half, when leading rusher Pierre Thomas sat out with bruised ribs.

Bucs quarterback Josh Freeman was 21 of 31 for 271 yards. He did not throw a touchdown pass and was intercepted twice, but made a pivotal play in overtime when he scrambled for a first down on third-and-6, sustaining the winning drive.

If Minnesota wins its final two games, starting tonight in Chicago, then the Saints will have to win in Carolina on Sunday to wrap up the first No. 1 NFC playoff seeding in franchise history.

"The most important thing to remember is we're 13-2, and the world is not over," Saints defensive tackle Sedrick Ellis said. "Tampa Bay's been running the ball all year. You can ask all the questions that you want, and the bottom line is we didn't get it done today."