ATLANTA — As an undrafted rookie running back was thrust into his first NFL start alongside Patrick Mahomes in a nationally prime-time game, Carson Steele had plenty of reasons to be nervous Sunday night.

One question, however, was unique and even sweet: What, he worried, if his football success distracted his family and friends from his sister Kesslar's wedding back in Indiana?

Carson's big day – 17 carries for 72 yards in the Chiefs' hard-fought 22-17 victory over the Falcons – was her big day, too. The date was set last year, long before her brother knew he'd have a work dispute in the NFL. It was one thing to miss his older sister's wedding, but quite another to inadvertently steal the show.

“I told her, 'If too many people are watching the game, turn off the TV,'” Steele said. “She was all for it. She went along with it.”

Steele, 21, has a towering personality — his long hair and incredible strength in the weight room earned him nicknames like “Fabio” and “War Horse” in college. He rushed for 1,556 yards and 14 touchdowns as a sophomore at Ball State University, then transferred to UCLA last year and ran for another 847 yards and six touchdowns. A slow 40-yard time — 4.77 seconds — kept him from being drafted, and he overcame the odds to make the Chiefs.

Why did Steele play such a big role Sunday night? That goes back to the “in sickness and in health” part of the Chiefs: Clyde Edwards-Helaire was already on the non-football illness list, and starter Isiah Pacheco broke his leg in last week's win over the Bengals, sidelining him for at least six weeks.

That left Steele, who made the Chiefs' 53-man roster primarily as a special teams player, veteran Samaje Perine and third-year running back Keaontay Ingram. Steele knew he would play a bigger role, but he didn't know how big his contribution to the Chiefs' offense would be.

Steele and Perine each had six runs in the first half – Steele for 26 yards, Perine for 25 – but in the second half, when they were initially down 14-13 to the Falcons, Steele had all the runs. His 17 runs were the most by an undrafted Chiefs rookie in the Super Bowl era, and on a night when Mahomes wasn't as productive as usual, Steele helped move the chains and keep Kansas City's offense on the field.

“I was a little nervous, of course,” he said. “I just had to calm down. This is the game I've played my whole life. It was really special. I had to land the first few shots, relax and get into it.”

As it turned out, the calming voice that helped him mentally prepare all week was his sister. They both had life-changing events coming up, and she helped Carson find a balance between focus and excitement for a big challenge ahead.

“She had a really rough week, so we talked back and forth,” he said. “She calmed me down and my parents talked to me too. When we started there, we had no idea what was going to happen, but there was just this 'next guy up' mentality.”

Steele had earned his spot on the roster through strong preseason runs, but that often happens against backups and players who are unlikely to remain on the final roster. He had played just 19 offensive snaps in the Chiefs' first two wins, but through summer workouts and training camp he had already earned a reputation as a hard worker among his teammates.

“He did a great job for us,” Pro Bowl center Creed Humphrey said after the game. “He's a really talented player. He's going to continue to improve and it's been great to watch him. He works really hard, studies really well and has done a great job. He prepares so well that he'll be ready when his name is called.”

The Chiefs will need Steele on more than just Sunday night. With Pacheco out for an extended period, Steele is in position to be their primary ball carrier. In the last 60 years, only four undrafted rookies have rushed for 1,000 yards: Dominic Rhodes of the Colts in 2001, LeGarrette Blount of the Bucs in 2010, Phillip Lindsay of the Broncos in 2018 and James Robinson of the Jaguars in 2020. The Chiefs' record for an undrafted rookie is 576 rushing yards, set by Mack Lee Hill in 1964.

Video clips from Indiana on Sunday night showed his sister's wedding reception and everyone watching the game cheering every time Steele appeared on camera.

Now the whole family – including his sister and new brother-in-law – can relax and enjoy his success as he chases his own ring.

“It's really amazing,” he said of their special day together on Sunday. “We got the win and she went into the game unmarried and left it married. I'm so happy and glad for her.”

Greg Auman is an NFL reporter for FOX Sports. He previously covered the Buccaneer for the Tampa Bay Times and The Athletic. You can follow him on Twitter at @gregauman.

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