P.J. Williams returned a game-clinching interception of Tom Brady for a touchdown as the New Orleans Saints surprised the Tampa Bay Buccaneers 36-27 on Sunday in New Orleans.

Trevor Siemian threw a touchdown after replacing injured Saints quarterback Jameis Winston, a former Tampa Bay standout, who was hurt in the second quarter.

The Saints had to turn to third-string signal caller Siemian because backup Taysom Hill was unavailable while recovering from a possible concussion.

Siemian completed 16 of 29 passes for 159 yards and drove the Saints 70 yards to set up Brian Johnson's 23-yard field goal, which gave New Orleans a 29-27 lead with 1:44 remaining.

Williams then stepped in front of a Brady pass and returned it 40 yards for a touchdown.

The Saints improved to 5-2 and are a half-game behind NFC South division leader Tampa Bay.

Brady completed 28 of 40 passes for 375 yards and four touchdowns for the Bucs, who were off to a club record 6-1 start.

Winston completed 6 of 10 passes for 56 yards, including a 16-yard touchdown to Tre'Quan Smith. Winston, who ran four times for 40 yards, injured his knee while scrambling after being tackled hard by Tampa Bay linebacker Devin White, who was whistled for a horse-collar tackle.

"I think it's significant," Saints coach Sean Payton said. "He felt something and is on crutches right now. When he got up and then had to go back down, you were a little concerned."

Tampa Bay took Winston as the top pick of the 2015 NFL Draft but he struggled with turnovers over five seasons before being dropped last year after Tampa signed Brady, who led them to the NFL title.