When Rex Ryan fired Tony Sparano as offensive coordinator in January, he knew he would have to have an uncomfortable conversation — not with Sparano, but with his son, Tony Sparano Jr.

Sparano Jr. had served under his father with the 2012 Jets as a coaching intern. Now, Ryan was firing Sparano Sr., but he wanted Sparano Jr. to stay with the Jets.

“I’m not going to lie, there was some awkwardness,” Ryan said recently, “but I knew I wanted to keep him.”

The conversation was a success, and Sparano Jr. stayed with the Jets despite his father’s dismissal. The 26-year-old is one of the few reminders around the 2013 Jets of his father’s one year as the team’s offensive coordinator.

The younger Sparano’s title officially is “seasonal intern,” but according to those on the Jets offense, he is the oil for their offensive engine.

“It’s huge,” quarterback Mark Sanchez said of Sparano’s role. “It goes unnoticed, unthanked, but it’s absolutely vital to a team’s success. Just for us to function you need Junior. If Junior gets sick, we’re not in good shape.”

Sparano Jr. declined to be interviewed, saying through a team spokesman that he prefers to remain in the background.

Sparano Sr. is now an assistant head coach and offensive line coach with the Raiders. He remains thankful the Jets could separate the evaluation of his job performance from that of his son.

“I’m glad my situation had nothing to do with him,” Sparano Sr. said by phone. “I’m glad Rex could see Tony’s value was completely different than mine. Tony’s his own man and he’s his own coach. He does a great job at what he does. He’s one of the best I’ve ever been around at what he does. It’s not because he’s my son. He’s just good at what he does. I think they saw his value.”

Sparano Sr. said he started bringing Tony Jr. to work when he was the tight ends coach with the Jaguars under Tom Coughlin.

At age 15, he began to learn how to break down film with his father, a skill that he utilizes with the Jets now.

“He does the job of a ton of guys,” Ryan said.

The job responsibilities for Sparano Jr. include scouting the opponent three weeks in advance. So, he currently is working on games the Jets will play in October. He compiles players’ “books” for that week, a three-ring binder filled with nearly 100 pages of scouting reports, offensive plays being installed that week and the game plan for every different type of situation.

He also works with the scout team in practice and assists quarterbacks coach David Lee.

Ryan saw quality and dedication in Sparano Jr.’s work that made him know he wanted to hold onto him.

“Quite honestly, Tony does a phenomenal job,” Ryan said. “He’s a young coach who works his butt off. It’s unfortunate the season we had last year, but I just wanted to make sure he wanted to stay. Once he did, there was no reason not to keep him.

“Obviously something like this we might be the first one ever to keep the son [after firing the father]. I do recognize it’s a little unusual.”

At a recent practice, Sparano Jr. stood a few yards away from Jeremy Kerley, who was catching punts. As the ball approached Kerley, Sparano Jr. would charge him and try to simulate an oncoming tackler. Kerley said Sparano Jr.’s work has helped build his confidence as a punt returner.

Sparano Jr. worked for his father with the Dolphins then the Jets. Sparano Sr. drew a lot of criticism after last season and was assigned a large amount of blame for the team’s 6-10 season, Sanchez’s failures and the failed Tim Tebow experiment. One of the Jets’ main objectives for 2013 was to improve the offense, a not-so-subtle shot at his father. Through it all, though, people around the Jets say Sparano Jr. has been able to separate his feelings as a son and as a coach.

“The way he was able to put those family ties aside and focus on this team is impressive,” Sanchez said. “It would be easy for him to get offended if somebody said, ‘Hey, we want to do this better this year.’ He could be like, ‘Whoa, that’s my dad.’ I could see how that could be a tough position, but he’s been a pro about it.”

Three thousand miles away, Sparano Sr. already is far removed from his experience with the Jets, but he still has one very strong tie to the organization.

“Rex was really good at the end of it,” he said. “He was able to separate the two [of us]. I didn’t want Tony to be there only because of me. That wasn’t why he was there. He was there because he was outstanding at what he did.”

Ryan agrees.