ATLANTA -- One week after squandering a 17-point halftime lead in a loss to Washington, the Tampa Bay Buccaneers nearly melted down again. But rookie quarterback Jameis Winston and an opportunistic defense saved the day.

Winston accounted for two touchdowns and led an overtime drive that set up Connor Barth's go-ahead, chip-shot field goal in the Buccaneers' 23-20 upset win over the Atlanta Falcons on Sunday at the Georgia Dome.

Winston converted on three third downs during the drive. The game didn't need to be that close, but this young Bucs' squad is still learning how to finish.

Tampa Bay (3-4) was in command late in the third quarter, up 20-3, but saw the lead trimmed to seven with just two minutes to play. That's when coach Lovie Smith gambled.

Facing a fourth down at the Bucs' 40-yard line with two minutes to play, Smith elected to go for it. After a timeout, Winston scrambled off play-action, pump-faked and dived for the first-down marker but was stopped short by Atlanta safety Ricardo Allen.

"If we punted the ball, we were going to have to stop them," Smith said of his decision to go for it on fourth down. "We had an opportunity to finish the game right then. I'd make that call 10 out of 10."

The Falcons took over with no timeouts and quickly marched to the Tampa Bay 8, where quarterback Matt Ryan found wide receiver Julio Jones in the back of the end zone for a touchdown. Matt Bryant's extra point tied score and sent the game into overtime.

The Bucs went into overtime with the memories of last week's blown lead fresh on their mind. But Barth delivered the go-ahead field goal, and Tampa Bay defensive end Howard Jones pressured Ryan on the Falcons' ensuing drive, forcing a fourth-down incompletion to seal the win.

"We would've liked to finish it when we could have," Tampa Bay receiver Mike Evans said, "but getting a win is all the same. Now we know how to finish and we need to finish every game."

Winston finished 16 of 29 passing for 177 yards with a touchdown and no interceptions. He also rushed for 24 yards, including a 4-yard scramble on third-and-goal that put the Buccaneers up 20-6 midway through the third quarter.

Ryan went 37 of 45 for 397 yards with two touchdowns and an interception. He squeezed a red-zone pass into tight end Jacob Tamme from 7 yards out to cut the Bucs' lead to 20-10 with 15 seconds left in the third quarter.

The Falcons (6-2) turned the ball over four times, with three coming in a sloppy first half. Jones lost a fumble after a long reception, an errant snap from center Mike Person ended an Atlanta drive inside the Tampa Bay 10, and Ryan threw a bad interception over the middle late in the second quarter.

After the interception, Ryan walked off the field, traded his helmet for a gray baseball hat and sat on the bench in disgust. He then watched Winston hook up with tight end Cameron Brate on a 20-yard touchdown pass that gave the Bucs a 13-3 lead at halftime. The Falcons went into the locker room to a chorus of boos from the home fans.

"Three of the four turnovers were on the plus-side of the 50," Ryan said. "That's directly taking points off the board. I thought we battled. We did kind of everything we wanted to offensively, other than protect the football."

Tampa Bay rookie linebacker Kwon Alexander had the strip of Jones and the interception of Ryan to help the Bucs improve to 2-1 against NFC South opponents. Alexander finished with a team-high 11 tackles, just days after his younger brother was killed in a fight in Alabama.

"It has been hard losing my little brother," Alexander said. "But I know that he would want me to be strong for him, so I came out here and dedicated this game to him. I'm just ready to get back to my family now."

Jones finished with 162 yards on 12 catches with a touchdown. Atlanta outgained Tampa Bay 496-290 but fell to 0-2 against NFC South opponents. The Falcons have lost two of three, after starting 5-0.

"We'll improve in a number of areas as we're going forward," first-year Atlanta coach Dan Quinn said. "That's kind of our theme each week. From a toughness standpoint and where we want to be, there's a lot of work for us to do, but I have all of the faith in these guys and belief in them to take it as far as we can."

NOTES: Atlanta saw both of its starting corners go down with injuries. Desmond Trufant took a hard fall trying to defend a deep pass in the third quarter. He left the field with a lower back injury. Robert Alford suffered a groin injury in the second half. ... Atlanta S William Moore and WR Leonard Hankerson -- both starters -- were inactive. ... With veteran WR Vincent Jackson inactive, rookie WR Donteea Dye started for Tampa Bay. ... Buccaneers veteran CB Tim Jennings was inactive for the second straight game. Jennings started the three previous games. ... Atlanta RB Devonta Freeman had his three-game streak of rushing for at least 100 yards snapped. Freeman finished with 88 yards.