It sounds like Coulson won’t be cool with his replacement in “Marvel’s Agents of S.H.I.E.L.D.” Season 4. Jason O’Mara, who is playing the mysterious new boss, teased the tense relationship on the ABC series.

“Obviously, the relationship between my character and Coulson [Clark Gregg] is going to be huge,” O’Mara revealed to the Hollywood Reporter. “It’s a power struggle kind of dynamic there. It's going to be huge and important.”

In the flash forward at the end of last season, Coulson was revealed to be reporting to someone else. As previously reported, it seems Coulson was replaced. S.H.I.E.L.D. will go public again, and since the fan-favorite character technically died in “The Avengers,” he can’t officially be the face of the organization.

It’s not just Coulson that the new director has to get along with, though. The new guy will have all the agents — with the exception of the rogue Daisy (Chloe Bennet) — working for him.

“And of course, how my character interacts with the entire team and their dynamic, but even their goals and purpose as a team, that’s going to be really interesting to see as that changes, if that changes,” O’Mara added. “And I had a scene with Elizabeth [Henstridge, who plays Simmons] this week and she is so funny and charming and sweet. My character is going to lean on her quite a bit to make sense of a lot of the science stuff because he’s new and needs it to be turned into laymen’s language.”

Simmons receives a promotion to Special Advisor to the Director in Science and Technology that allows her to work closely with the new director. However, her fellow agents won’t appreciate her new friendship with the director. “Fitz [Iain De Caestecker], as well as her former team members, finds it hard to confide in or trust her since she’s now the director’s confidant,” the synopsis for the season reveals.

Fans might be able to find out more about the director’s intentions when his identity is revealed. Marvel will only say that the Season 4 character was introduced in the comics in the 1940s. “He has roots in Marvel history,” O’Mara teased. “We know that he’s out there already. He pre-exists. But no doubt [the writers] will do their own modern spin on it, as they do.”

“Marvel’s Agents of S.H.I.E.L.D.” Season 4 premieres Tuesday, Sept. 21, at 10 p.m. EDT on ABC.