SANTA CLARA, Calif. (AP) - Cam Newton threw a pair of touchdown passes following San Francisco turnovers and the Carolina defense shut down Kyle Shanahan's offense in his coaching debut as the Panthers beat the 49ers 23-3 Sunday.
Newton threw a 40-yard touchdown pass to Russell Shepard in the first half following a fumble by Brian Hoyer, then a 9-yard touchdown to Jonathan Stewart in the third quarter after Luke Kuechly intercepted Hoyer.
PHOTOS: Panthers vs. San Francisco 49ers
That helped the Panthers get off to a good start in the season opener following last year's disappointing 6-10 finish. Despite the touchdowns, Newton did not look particularly sharp after playing just one series in the preseason as he recovered from surgery to repair a partially torn rotator cuff.
Newton was off-target on numerous throws, including missing a wide-open Ed Dickson in the end zone in the first half. Carolina had to settle for a field goal on that drive. Newton finished 14 for 25 for 171 yards.
Those mistakes didn't matter against a Niners team that didn't look much improved from last year's outfit that tied a franchise worst with 14 losses. That led to the firing of coach Chip Kelly and general manager Trent Baalke.
Shanahan and new GM John Lynch each got six-year contracts to oversee a massive rebuilding job . There is plenty of work to do as San Francisco was held scoreless in the first half of the opener for the first time in 40 years and lost the first game of the year for the first time since 2010. The Niners finished with just 217 yards of offense.
Hoyer had a rough debut for San Francisco, throwing for only 193 yards and committing the two turnovers.
Carolina first-round pick Christian McCaffrey had an up-and-down debut. The former Stanford star gained 45 yards on 13 carries and added five catches for 38 yards. He also lost a fumble in the fourth quarter.
Shanahan went twice on fourth down in the first half and failed. Hoyer was sacked by Thomas Davis on fourth-and-4 from the Carolina 44, and Kyle Juszczyk was stuffed by Star Lotulelei on a fourth-and-1 from the 45. The Panthers turned those short fields into a pair of field goals. San Francisco converted one of two fourth-down attempts in the second half.
The Panthers put heavy pressure on Hoyer and had four sacks, including one by Wes Horton that forced a fumble by Hoyer. Carolina finished second in the NFL last season with 47 sacks.
San Francisco safety Jaquiski Tartt had a wild first half that included a missed tackle on Shepard's touchdown, a personal foul for unnecessary roughness, then an acrobatic interception near the goal line on a deep pass to Kelvin Benjamin.
Niners rookie linebacker Reuben Foster had an impressive debut cut short when he injured his right ankle late in the first quarter. Foster got hurt on a run by McCaffrey and was taken to the locker room on a cart. He returned to the field a few minutes later, but didn't get back in the game. Foster had three tackles and a pass breakup before the injury. Shepard caught his TD on the play after Foster left.
Panthers: Host Buffalo next Sunday.
49ers: Visit Seattle next Sunday.