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 two 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 in a row
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.
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 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.
Falcons running back Michael Turner ran 16 times for 50 yards, and Jason Snelling finished with 31 yards on seven carries.
"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."
Ryan completed 26 of 43 passes for 273 yards.
Late in the second quarter, Tony Gonzalez caught a 9-yard pass to become the first NFL tight end with 12,000 yards receiving. Gonzalez spent his first 12 seasons in Kansas City before the Falcons traded for him last year.
Frank Gore finished with 137 total yards, 77 rushing on 21 carries and 60 yards receiving on seven catches for the 49ers. Smith completed 21 of 32 passes for 188 yards and a touchdown.