CHARLOTTE, NC – Ray McDonald's 31-yard interception return for a touchdown seemed to be what the 49ers needed to break through and get their first road win of the season.
But while Matt Moore's critical error cost Carolina the lead, it didn't cost the Panthers the game.
After the mistake, the embattled quarterback went on to rally his teammates with 10 unanswered fourth-quarter points in a 23-20 win over the 49ers.
"I thought we were on track," head coach Mike Singletary said after his team fell to 1-6 on the year. "They hung in there and played tough. We have to regroup."
On McDonald's pick six, the 290-pound defensive tackle jumped a screen pass and ran 31 yards down the left sideline behind several blockers en route to the end zone.
But with a seven-point lead, the 49ers defense could not stop Moore and his young receivers when it mattered most. Moore marched the Panthers down the field after his only turnover of the game and tossed a 23-yard touchdown to rookie wideout David Gettis.
"They executed and we didn't," cornerback Shawntae Spencer said. "We made crucial mistakes at the end of the game.
"It's one of those things where it's they made the plays when they had to."
The 49ers scored on their opening possession when Alex Smith threw a one-yard touchdown pass to tight end Vernon Davis, but they failed to find the end zone offensively after that point.
Smith suffered a sprained left shoulder in the opening possession of the second half, X-rays came back negative, but the loss of Smith was difficult to overcome.
David Carr stepped in for Smith in the second half and completed 5-of-13 passes for 67 yards and one interception. His late-game turnover proved to be costly as it set up John Kasay's game-winning field goal from 38 yards out.
"I just tried to throw it behind him, but Rich (Richard Marshall) made a play and realized the ball was coming," Carr said. "He made a good play."
After the game, Singletary didn't say which quarterback would start when the 49ers host the Denver Broncos in London next Sunday. Smith was 9-of-19 for 129 yards before the injury.
"As soon as I landed on it, right away (I knew)," Smith said of the injury to his non-throwing shoulder. "I stood up and was seeing if I could go to the next play, knowing it was my left arm. But I knew, that's why I went back down."
Panthers defensive end Charles Johnson got around the right edge to sack Smith, landing on Smith's left shoulder as he finished the play. As a result, Carr came in as the replacement to see his first action of 2010.
Thanks to a forced fumble and recovery by Spencer, who stripped wide receiver Steve Smith at midfield late in the third quarter, the 49ers seemed to be in good position for Carr to lead his first scoring drive of the year. The drive resulted in points, but no touchdown as they tied the game at 13 with a Joe Nedney field goal.
That field goal would be last offensive points the 49ers scored on a day in which Frank Gore rushed for 102 yards on 19 carries.
After Davis' early touchdown reception, which was set up by a 53-yard play-action pass to the tight end, the Panthers took over and got onto the scoreboard courtesy of a 47-yard Kasay field goal.
But the 49ers defense came up with a big turnover early in the second quarter when cornerback Nate Clements stripped DeAngelo Williams along the Panthers sideline. Linebacker Parys Haralson recovered it for the 49ers.
With the ball at midfield, the offense moved into the red zone but could not score a touchdown. Nedney converted a 24-yard field goal to give the 49ers a 10-3 lead with 8:44 remaining in the half.
This was the 49ers first loss under Singletary when winning the turnover battle.
Penalties, however, continued to hurt the 49ers. San Francisco committed 11 penalties to the Panthers four.
Two pass interference penalties, first on safety Taylor Mays and then on cornerback Will James, helped Moore complete an 18-yard touchdown pass to Gettis in the second quarter which tied the game at 10. The rookie became the first Panthers receiver not named Steve Smith to catch a touchdown pass this season. He finished with a game-high eight catches for 125 yards and two touchdowns.
This wasn't the outcome the 49ers expected, but they vowed to bounce back as they head to London to take part in the NFL's International Series.
"Right now it's a matter of getting our guys regrouped," Singletary said. "We know there's a lot of football to be played, we just have to regroup and make sure we have the right people in place to help win football games.
"That's bottom line right there."