T.J. Yates might be a mystery to most of the Jets on Sunday, but at least one of them is very familiar with the Texans’ fill-in at quarterback.

Linebacker Quinton Coples played alongside Yates for three seasons at North Carolina, and Coples is here to warn everyone his former college teammate won’t be an easy mark for the Jets this weekend when they visit Houston.

Yates — who, incredibly, remains the only Tar Heels quarterback ever to take a snap in the NFL — showed that last Monday night by taking over in relief of a concussed Brian Hoyer and throwing a 22-yard touchdown pass to DeAndre Hopkins for what proved to be the winning points in a 10-6 road upset of the previously unbeaten Bengals.

Throw in the fact Yates also was the first passer in the Texans’ brief history to win a playoff game, and Coples says the Jets can’t expect a cakewalk just because Houston is starting a quarterback who was unemployed just three weeks ago.

“He won a playoff game for them,” Coples said, referring to the Texans’ 31-10 victory over the Bengals in January 2012. “I mean, he’s not just some guy off the street. That’s something we’re going to have to keep in mind. It’s not just some no-name backup we’re going against out there.”

It’s not as if the Jets can counter Yates with a postseason stalwart at the position, either. Ryan Fitzpatrick has never even appeared in a playoff game in 11 NFL seasons, much less been the starter in a victory.

To be sure, Yates is no Aaron Rodgers — or even a permanent No. 1, for that matter.

Sunday will be just the sixth regular-season start of Yates’ five-year career and his first since a playoff loss to the Ravens in January 2012. The Texans traded him to the Falcons last year. After being cut by Atlanta in September, Yates was out of football when the Texans called to have him back up Hoyer following headcase Ryan Mallett’s recent meltdown.

But the 6-foot-4, 217-pound Yates is resilient, if nothing else, and Coples said the Jets can’t expect Yates to go quietly Sunday.

“He’s going to compete, man,” Coples said. “He’s going to keep fighting, regardless of the situation. That means we’re going to have to keep getting after him. The key is going to be hitting him early and putting him off-balance.”

Yates has a strong arm — Jets coach Todd Bowles described it as a “cannon” on Thursday — to go with his pro-type size, not to mention one of the league’s most dangerous receivers in Hopkins. As if that won’t be enough of a test for a struggling Jets defense, Coples describes Yates as a solid package with deceptive elusiveness.

“He throws a good outside ball and can really put it on point on fade routes and outside routes and stuff of that nature,” Coples said. “What he does best, though, is extend the play. He’s not as mobile as some of the more mobile quarterbacks, but he’s definitely a guy you have to keep an eye on and keep contained.”

According to Coples, who is still in friendly contact with Yates, the Jets can also expect some trash talk if things go Yates’ way Sunday.

“He’s a little fiery,” Coples said. “You’ll see him jumping around after big plays, and he’ll talk to you a little bit if he does something good. He definitely won’t be a robot out there, that’s for sure.”

Yates also is a quarterback entirely capable of beating the Jets, as Coples readily admits.

“He’s not a top-tier guy who’s going to blow you away, but he’s going to do his job and fight and scrap and keep his team in the game,” Coples said. “Underestimate him only if you dare.”