Alex Smith found himself under pressure frequently. (Ed Zurga / Associated Press)

The late, low hit on Kansas City Chiefs quarterback Alex Smith is going to cost Pittsburgh Steelers safety Mike Mitchell dearly.

Mitchell has been fined $48,620, according to ESPN’s Adam Schefter, for the hit that left Smith fuming days after the Chiefs’ loss — a large sum that Mitchell plans to appeal. Mitchell, who had been tripped by teammate Anthony Chickillo, hit Smith from behind just as he released a pass in the third quarter, just missing a sack. The hit caused Smith to yell at Mitchell and, two days later, he hadn’t mellowed.

“I felt like it was extremely late,” Smith told the Kansas City Star. “I felt there was nothing done there to avoid contact. It was really low from the backside. I thought it was about as flagrant as it gets when it comes to a low hit on the quarterback.”

Mitchell was flagged for roughing the passer, but defended his move, saying “I’m not a dirty player.”

“I wasn’t trying to take Alex Smith’s legs out,” Mitchell said. “I went up to him and told him that. It’s just one of those things you don’t want to see in a football game. If you watch the tape, I’m even trying to turn my body as I’m falling. Alex is backpedaling into me. I wasn’t even going in the direction of Alex. He’s actually throwing it and fading away.”

Mitchell also sent Charcandrick West into concussion protocol with a helmet-to-helmet hit in the game and was twice fined in 2015 for similar plays. An unnecessary roughness penalty against Antonio Gates cost him $8,681 and his hit on Tyler Eifert, a defenseless receiver, cost him $23,152.

Read more from The Post:

A tiny Pistons crowd boos Kid Rock, cheers Eminem

Nets’ Jeremy Lin is out for the season, already

The NBA’s Nike jerseys haven’t been a rip-roaring success

Spurs stand for national anthem, then take a stand with a scoreboard message