KANSAS CITY, Mo. — The Chiefs' Patrick Mahomes is just as efficient at home as he is on the road.
He gets the same results, too.
After winning his first three starts, all away from Arrowhead Stadium, the second-year pro finally made his regular-season home debut Sunday. Mahomes responded by torching San Francisco's banged-up pass defense for 314 yards and three touchdowns in a 38-27 victory over the 49ers.
Mahomes now has 13 touchdown passes without an interception, breaking the NFL record for TD passes in the first three weeks of a season. Peyton Manning threw 12 to start the 2013 campaign.
Mahomes' touchdown passes to Chris Conley, Demetrius Harris and Sammy Watkins , along with a pair of TD runs by Kareem Hunt, helped Kansas City (3-0) race to a 35-7 lead late in the first half.
Few leads are safe against the Chiefs' porous defense, though.
The 49ers (1-2) rallied behind running backs Matt Breida and Alfred Morris, who kept gouging the Chiefs' defensive front, and Jimmy Garoppolo, who threw for 251 yards and two scores . It was Garoppolo's 11-yard pass to Marquis Goodwin early in the third quarter that started the comeback, and Morris scored on a short touchdown run later in the quarter to make it 35-24.
After the Chiefs tacked on a field goal early in the fourth to extend their lead, the 49ers came back with a grinding, 17-play drive that wiped out more than half the period. But it ended in a strange sequence that began with Garoppolo taking a hard hit from Steven Nelson along the sideline. Garoppolo easily could have stepped out of bounds, but instead he was crushed on his throwing shoulder and had to leave.
C.J. Beathard came in and threw what appeared to be a fourth-down touchdown pass to George Kittle, but it was wiped out by offensive pass interference.
There was only 5:17 left, but rather than go for it on fourth-and-goal at the Kansas City 25, 49ers coach Kyle Shanahan elected to kick a field goal — keeping it a two-possession game.
San Francisco proceeded to kick it deep rather than try an onside kick. The Chiefs picked up a first down on a penalty, and Hunt churned his way for two more first downs to put the game away.
The 49ers have not won in Arrowhead Stadium since Dec. 26, 1982.
49ers LB Reuben Foster had a rough return from a two-game suspension for violating the league's personal conduct and substance abuse policy. Foster was hit with a personal foul for hitting Mahomes as the QB was sliding in the first half, Kelce beat him in pass defense, and the young linebacker left early in the fourth quarter when he was shaken up on a tackle.
49ers: The defensive backfield was in tatters by the fourth quarter. CB Richard Sherman left with a calf injury, FS Adrian Colbert hurt his ankle and backup CB Tarvarius Moore left with a wrist injury. SS Jaquiski Taylor was already inactive with a shoulder injury.
Chiefs: LB Dee Ford left with a groin injury in the fourth quarter. ... Conley briefly left with a right ankle injury, though he returned to make his TD catch. ... SS Eric Berry (heel) remained inactive for the third straight week. He has not practiced since early in camp.
49ers: Play the Chargers in Los Angeles next Sunday.
Chiefs: Visit the AFC West-rival Broncos next Monday night.