San Diego ? Things are going so well now for the Kansas City Chiefs that they have a 346-pound defensive tackle leaping over the pile into the end zone.

Big Dontari Poe scored a one-yard touchdown on fourth down, and linebacker Justin Houston intercepted Philip Rivers and returned it 17 yards for a touchdown as the Kansas City Chiefs embarrassed the free-falling San Diego Chargers 33-3 Sunday.

With Alex Smith victorious again at Qualcomm Stadium, the Chiefs (5-5) won their fourth straight game following a five-game losing streak.

The Chargers (2-8) lost their sixth straight.

The Chiefs brought some defensive heat, even on offense.

After Charcandrick West was stuffed from the one-yard line on third down on the Chiefs’ second possession, they went on fourth down, this time giving the ball to Poe. He got air and went in for his first NFL TD.

“I smelled the end zone, man,” he said. “At that point you’ve got to do whatever you need to get in there. I saw a couple of bodies there and didn’t want to take a chance. So I just did it man.”

The Chiefs have had the play in their playbook for a few years.

Poe is the heaviest NFL player to score an offensive touchdown, according to STATS.

“I needed it. I loved it. My eyes lit up,” Poe said.

“We keep putting him in as a blocker. I told him we’d give him the ball,” coach Andy Reid said. “I didn’t know he was going to jump over.”

Said Houston, with a laugh: “I told him I earned my touchdown. His touchdown was given.”

It was Houston’s first TD, as well.

“I was happy because we got a touchdown and it gave us seven points,” Houston said.

Houston had four of Kansas City’s seven sacks of Rivers in the 2014 season finale in which the Chargers were eliminated from the playoff race.

The Chargers pretty much melted down. Rivers had his worst game of the season, going 19 of 30 for just 178 yards. Tight end Antonio Gates was seen jawing at the quarterback on the sideline in the first half.

“Really what was said really doesn’t matter,” Rivers said. “Brothers fuss and fight, for any of you that have brothers. And I Iove Antonio and I think he will tell you the same thing.”

Rivers said Sunday’s face-plant “is about as tough as it gets and not like it hasn’t been tough the last five. This one, it gets even worse.”

Smith, who led Helix High to consecutive city championships at Qualcomm Stadium, completed 20 of 25 passes for 253 yards. He also ran seven times for 33 yards.

There’s a chance this was Smith’s last appearance at Qualcomm Stadium. Chargers chairman Dean Spanos has infuriated fans with his intention to move the team to an industrial suburb of Los Angeles, which would require approval of fellow owners.

“To have been able to play here and play high school football, it was a big deal,” Smith said. “To come back and play in college and in the pros, it’s been special.”

Smith broke Steve DeBerg’s team record of 233 consecutive passes without an interception. Smith threw his 234th straight pass without a pick on a 47-yard completion to running back Charcandrick West. Smith extended his record to 253.

The Chiefs turned to Poe to cap their second drive. The 6-foot-3 defender soared for a 6-0 lead. The PAT failed.

Cairo Santos kicked field goals of 28 and 24 yards, and Spencer Ware had two three-yard TD runs in the fourth quarter.

San Diego’s only score was a 52-yard field goal by rookie Josh Lambo.

NOTES: At halftime, the Chargers inducted running back LaDainian Tomlinson into their Hall of Fame and retired his No. 21. … Chiefs WR De’Anthony Thomas suffered a concussion and West strained a hamstring. … For the Chargers, DT Sean Lissemore and S Jahleel Addae had concussions. RT Joe Barksdale had a hip injury. … This is the Chargers’ 20th non-winning season in 32 years of Spanos family ownership,