ATLANTA -- Mike Smith knew it could happen again.
A week ago, his Atlanta Falcons blew a 20-point lead but won through a miracle comeback in the final minute.
Again on Sunday in the NFC Championship Game, the Falcons built a big lead -- 17 points at one point. Smith said his message at that juncture was to "never let up, never give up."
"That's how you have got to play this game," he said. "In the National Football League, you have to play for four quarters."
The Falcons learned that lesson painfully on Sunday in a 28-24 loss to San Francisco at the Georgia Dome as second half turnovers, one an example of bad luck the other of dumb luck, proved their undoing.
The Falcons, playing in their first conference championship game since 2005 and hoping to go to their first Super Bowl since 1999, still have many bright young stars -- wide receiver Julio Jones with a break-out performance on Sunday and quarterback Matt Ryan among them -- but one has to wonder if their window to win a Super Bowl is getting smaller as another year passes and critical players like Tony Gonzalez and Michael Turner might have played their final games in a Falcons uniform.
On consecutive possessions in the third quarter with Atlanta leading by 24-21, the Falcons turned the ball over -- both times on the 49ers' half of the field -- and those plays could have made the difference between winning and losing in such a close game. San Francisco only had one turnover, as the Falcons finished minus-1 in the turnover margin.
During the regular season, Atlanta's plus-13 mark tied for the fifth-best in the league.
"When you don't win the turnover ratio in the playoffs," Smith said, "you're not going to win the football game."
The first one came on second down-and-10 from the 49ers' 47. Roddy White went into a break on his route but fell down. Ryan had already released the ball and 49ers nickelback Chris Culliver picked it off with 7:38 left in the third.
After the 49ers took over, David Akers hit the left upright on a 38-yard field goal try, the ball bouncing out, but the Falcons felt they lost an opportunity to put some points on the board.
"That one's all on me," White said. "It was a crucial point in the game because we were kind of driving, probably going to score some points. That was a tough turnover."
The second one proved even more costly, as the Falcons already sat in field goal range. The miscue was even more uncharacteristic.
On the ninth play of a drive at the 49ers' 28, Ryan set up in the shotgun and fumbled the snap. Aldon Smith recovered with 55 seconds left in the third.
If the Falcons held on for a field goal there, they could have kicked a short field goal to take the lead with 1:13 left in regulation on fourth down and 4 from the 49ers' 10 -- a play that failed as NaVorro Bowman defensed a pass to White that ended Atlanta's chances to win.
Ryan called the fumble a "freak play."
"Took my eyes off the ball for a second and it ended up on the ground," he said, "and against a good football team like that you can't have those kinds of mistakes. You have to capitalize on those opportunities -- two chances in positive territory and didn't come away with points.
"When you do that, you're not going to win."
The Falcons are still in good shape with Smith having guided them to playoff berths in four of his five seasons, but in terms of personnel it might not be the same rosy outlook. Gonzalez -- one of Ryan's favorite targets -- looks as if he played the final game of his brilliant career on Sunday.
He even asked the media for more time so he could compose himself before speaking.
"Emotional," he said. "That's probably going to be the last time I wear that uniform or football pads and cleats. I didn't want to take it off, tell you the truth. All good things come to an end and like I said all season long this is probably my last one. But what an unbelievable ride."
In addition, running back Michael Turner, a mainstay for the Falcons since Smith arrived, is not assured of returning, as his production has diminished with increasing age and the physical toll of more than 1,400 carries over the last five seasons.
Defensive end John Abraham, perhaps the Falcons' most dynamic and productive defender with 10 sacks and six forced fumbles, will be 35 next season.
If nothing else, Falcons general manager Thomas Dimitroff has shown himself adept at drafting and acquiring talent, a record envied by others in the league. Each of the last two seasons, a member of his staff has departed to become a general manager with another team (Les Snead to the Rams last year and David Caldwell to the Jaguars this season).
To pry that window open larger, the Falcons will have to continue to reload. If not, it could be another eight years before they reach their next NFC Championship again.