49ers vs. Chiefs: Matt Breida injured, poor play leads to huge first-half deficit

The San Francisco 49ers' Week 3 road contest against the Kansas City Chiefs got off to about as bad a start as possible, leading to the Niners trailing 35-10 by halftime.

The San Francisco 49ers defense figured to be in trouble against the red-hot Kansas City Chiefs and their explosive offense, which proved to be the case over the first half of Week 3 at Arrowhead Stadium.

After going 3-and-out on their own opening offensive drive, the Niners quickly gave up an 11-play, 57-yard drive that culminated in a 1-yard touchdown run by Chiefs running back Kareem Hunt. San Francisco's porous defense gave up 14 yards on a Chiefs 3rd-and-15 screen play and subsequently allowed Kansas City to convert the fourth-down try.

The Chiefs scored again on their following possession, another 1-yard run by Hunt during which he wasn't even touched.

San Francisco answered back, however, with quarterback Jimmy Garoppolo finding fullback Kyle Juszczyk for a 35-yard touchdown pass off play action. That cut the deficit to a 14-7 score.

But the Niners defense, which had struggled with tackles all throughout the first half, couldn't respond and allowed a quick five-play, 75-yard drive that lasted a mere 2:58 on the clock, culminating with an impressive touchdown pass from Chiefs quarterback Patrick Mahomes to wide receiver Chris Conley.

Seriously, it was insane to see Mahomes evade the pressure and hit his mark:

Poor tackling, angles and penalties doomed the Niners' first-half efforts too. Over the first half, San Francisco was flagged nine times for a whopping 106 yards -- not the formula, particularly on defense, going up against the NFL's top-ranked offense entering the contest.

And those penalties led to the Chiefs' fourth touchdown of the first half -- a 13-yard pass from Mahomes, which gave him 12 touchdown passes to start the season.

With just over three minutes remaining in the half, running back Matt Breida suffered an apparent non-contact, right knee injury. That's about as big a problem for what's turned into an inept San Francisco offense against a poor Chiefs defense.

The bad gets even worse, although Breida was seen running and cutting on the sideline late in the half. But cornerback Richard Sherman (leg) exited the game, according to NBC Sports Bay Area's Matt Maiocco.

Kansas City will start off on offense in the third quarter with a more-than-comfortable 35-10 dominant lead after Robbie Gould tacked on a 39-yard field goal to close out the ugliest half for San Francisco thus far in 2018.