ATLANTA -- Roddy White's best play came on defense, and it allowed the Atlanta Falcons to come up with another close-call victory.
When 49ers cornerback Nate Clements intercepted Matt Ryan late in the fourth quarter and ran 39 yards down the left sideline, White had one goal in mind: Knock the ball out.
"Any time that you see defensive players carrying the ball," Atlanta's star receiver said, "they aren't used to it, so you've got a chance."
White's forced fumble kept the winning drive alive, and Matt Bryant kicked a 43-yarder with 2 seconds remaining to lift the fortunate Falcons to a 16-14 victory over the winless 49ers on Sunday.
"It wasn't the prettiest kick," said Bryant, who won last week's overtime game at New Orleans with a 46-yard field goal. "But the only thing that matters is we get that 'W' when the ball went through the uprights."
The Falcons (3-1) have won three straight.
San Francisco (0-4) blew a 14-0 first-quarter lead due in part to a pair of interceptions by Alex Smith.
"Those were critical errors," Smith said.
White caught seven passes for 104 yards -- including four for 60 yards on the winning drive -- but his biggest play was chasing Clements down and knocking the ball loose as he tackled him from behind at the Atlanta 7.
Falcons guard Harvey Dahl recovered the ball to preserve the 12-play winning drive. Clements picked off a pass over the middle that was intended for tight end Tony Gonzalez.
San Francisco went up 7-0 in the first quarter on Vernon Davis' 11-yard touchdown catch. The 10-play drive was aided by cornerback Dunta Robinson's 34-yard pass interference penalty against tight end Delanie Walker.
Four plays later, Falcons punter Michael Koenen was lined up to receive a snap in the end zone. A blown blocking assignment allowed Dominique Zeigler to run past long snapper Joe Zelenka and dive forward for the blocked punt.
Taylor Mays, seeing the ball arching down in his direction, turned toward the back of the end zone and kept both feet inbounds as he caught the loose ball for an unconventional touchdown and a 14-0 lead.
"I saw him block it, picked it up and tried to keep my feet in bounds," Mays said. "It was a trip, but I would have given it all up for a win."
Falcons running back Michael Turner ran 16 times for 50 yards, and Jason Snelling finished with 31 yards on seven carries.
Ryan, who completed 26 of 43 passes for 273 yards, connected with Gonzalez to convert Atlanta's final third down on a 5-yard pass to the San Francisco 26.
Late in the second quarter, Gonzalez caught a 9-yard pass to become the first NFL tight end with 12,000 yards receiving. Gonzalez, who spent his first 12 seasons in Kansas City before the Falcons traded for him last year, earlier this season became the first NFL tight with 1,000 career catches.
He seemed more proud of White and Dahl for extending the winning drive.
"We knew we just needed a field goal, so we had to get it 20 yards past the 30-yard line," Gonzalez said. "It's definitely all confidence when you are in the huddle at that point."
The 49ers failed to hold the one-point lead despite running 13 plays and using nearly seven minutes of the fourth quarter, but the drive ended with Smith getting sacked on William Moore's unblocked safety blitz.
"On that last drive, I thought we did a good job," Smith said. "We were moving the ball, but then we stalled. It was frustrating not to be able to get points."
Though the game ended with another loss, the Niners' early drive gave hope that coach Mike Singletary made the right choice in firing Jimmy Raye as offensive coordinator earlier this week and replacing him with Mike Johnson.
"As much as it hurts right now, I'm excited," Singletary said. "There were positives that came from this."
Frank Gore finished with 137 total yards, 77 rushing on 21 carries and 60 yards receiving on seven catches. Smith completed 21 of 32 passes for 188 yards and a touchdown.
Atlanta was 2 for 11 on third down plays before Ryan threw from his end zone to connect with Brian Finneran for a 17-yard gain down the left side.
White made four tough catches on the drive. His 19-yard reception against safety Dashon Goldson came in tight coverage on the left side before Ryan's second interception.
After he helped the Falcons regain possession, White ran a sideline route on the right side and beat cornerback Tarell Brown for a 20-yard gain.
"It was an incredible catch," Ryan said. "The ball had pace on it. It was high, and he went up and just made a played when we needed to. That's the kind of thing we've come to expect from Roddy."
Early in the second quarter, Harry Douglas caught Ryan's 8-yard pass in the right flats and dove for the front pylon to cut the lead to 14-7.
Douglas' 34-yard catch late in the second quarter helped set up a 37-yard field goal by Bryant that made it 14-10 at halftime. Bryant cut the 49ers lead to 14-13 with a 31-yard field goal at the 5:53 mark of the third quarter.
"We made lots of mistakes and we've got lots of things that we've got to correct," Falcons coach Mike Smith said. "But we're 3-1 through the first quarter of the season."
Notes: 49ers S Michael Lewis didn't make the trip. He missed practice Friday because of personal reasons and reportedly has demanded a trade. Mays started in his place. ... Falcons WR Michael Jenkins (shoulder) and OLB Sean Weatherspoon (ankle) did not dress. ... X-rays of Walker's sprained ankle were negative. He didn't return after leaving in the second quarter.