PITTSBURGH – This much is known: Mike Mitchell and Steve Smith Sr. were Carolina Panthers teammates for one season in 2013.

Whether the two were ever on friendly terms is not clear, though Mitchell did tell The Times in a September 2014 interview -- before Smith’s first game against the Steelers with the Baltimore Ravens — that: “I’m going to give him a big hug before the game, and then we’re both going to try and rip each other's head off.”

Well, neither hugs nor Christmas cards will be exchanged Sunday when Mitchell’s Steelers host Smith and the Ravens at Heinz Field. As for ripping each other's head off, that’s a possibility.

How has such a, um, beautiful friendship gone sour?

“I don’t know,” Mitchell said this week. “You’d have to ask him.”

As if the Steelers-Ravens rivalry with a division championship on the line needed any more buildup, the Mitchell-Smith feud adds even more drama. It started, apparently, when Smith injured his back last season on a hit from Steelers linebacker Lawrence Timmons.

What does that have to do with Mitchell? The Steelers safety was in the area of the play, and according to Smith, who was unaware that Timmons hit him, Mitchell said: “How you like that?” That, apparently didn’t sit well with Smith, who later told reporters that his former teammate was on his “lifetime hit list.”

True to his word, Smith has targeted Mitchell for abuse this season. Though an offensive player is at a distinct disadvantage in exacting physical revenge, Smith took great joy in the Ravens’ 21-14 Week 9 win. Smith pulled in four catches for 47 yards, shedding a Mitchell tackle on a 30-yard gain. The two nearly came to blows near the Ravens sideline after the Steelers’ onside kick failed in the waning seconds, and afterward Smith compared Mitchell to a “cabinet.” Whatever that means.

“I am a foundation builder. He is a cabinet. That is the PG version,” Smith said. “Any time I mention his name, it just increases who he is. He is not much. He was a teammate of mine, but at the end of the day, I’m a Baltimore Raven and I have done a lot of things in this league.

“He ain’t on my level. He never will be. He is not even on the same level as my kids. So, I am not even going to concern myself with him until the cabinets come in.”

In addition to being a world-class trash-talker, Smith is a likely future Hall of Famer. The 37-year-old is seventh all-time with 14,618 receiving yards, and is second on the Ravens with 686 yards and four TDs this season. The diminutive receiver, 5-foot-9, 185-pound receiver plays as big as his mouth.

“He gives you everything under the sun,” said cornerback Ross Cockrell. “He’s a guy that, he just does not like being covered. So, he’s going to do whatever it takes to break a tackle, whatever it takes to get open and that’s what makes him tough. I think he was (Antonio Brown) before (Brown).”

No one is spared from Smith’s wrath. Cockrell said he’s heard from Smith, too, but doesn’t engage in trash talk. The Duke grad joked that he isn’t about to drop some Pythagorean theorem knowledge on Smith.

“You’re not going to discuss the A-square, B-square equals C-square,” Cockrell said. “Definitely not discussing that. It’s just straight football.”

While Mitchell and Smith are on the outs, Cockrell said the two are similar in their passion. Mitchell, a respected veteran and an intimidating presence in the secondary, isn’t going to win many popularity contests outside of Pittsburgh.

“Mike Mitchell, he takes the same approach every single week,” Cockrell said. “He doesn’t back down from anybody and he wants to be an enforcer on this steam. That’s what we’re looking for on the D this week.”

As for Sunday’s game, and a chance to possibly end Smith’s last chance at a Super Bowl, Mitchell was keeping mum.

“I just look forward to playing the AFC North championship game,” Mitchell said.