PITTSBURGH -- After months of contentious negotiating and a fast-approaching deadline to get a deal done with the Steelers, T.J. Watt on Friday expressed joy that the saga was over.

The 26-year-old star edge rusher officially signed a five-year deal with the team Friday to become the NFL's highest-paid defensive player. The new four-year extension is worth $112 million and includes a $35 million signing bonus and $80 million guaranteed over the next three years, a source told ESPN's Jeremy Fowler.

It is the largest signing bonus in team history.

"Man, I've been dealing with pressure my whole life," Watt said about trying to live up to the pressures of the record-setting deal. "... I'm built for this. And I truly believe that nothing monetary will change me as a person. The work that I put in will not change. It will only grow. ...

"It's my job to prove all these people that have put this amount of money to me and stood on the table to say they want me here, to prove them right. I know I can do it. I know exactly what it takes. I've been doing it my whole life. It's just about continuing to do it and staying hungry. And I guarantee everybody here right now and everybody in this building, I am still hungry."

After Friday's practice, coach Mike Tomlin, who remained optimistic throughout the process that a deal would get done, also was happy that it got done before Sunday's season opener at Buffalo.

"There's a sense of relief, to be quite honest with you," Tomlin said. "We can get focused on this. Not that we haven't been, but in circumstances like this, I field a lot of questions regarding it, and I like to focus my energies on the Buffalo Bills. He's deserving. We're glad to have him. It's good for all parties involved."

Watt, speaking to the media for the first time since the first day of training camp, thanked his teammates for their support throughout the process.

"When you go through something like this, and you're trying to stand up for what you believe in and you're doing it by yourself, having reassurance from the people that you care about their opinion the most means a lot.

"And there are definitely some moments through this whole process where you do feel like you're almost by yourself. And that's why it's so important that those guys said those nice things."

Watt expects to play Sunday and feels "great." He worked closely with the Steelers' strength and conditioning staff throughout training camp, when he mostly worked off to the side during team periods.

When asked whether he would've played Sunday even without a deal, Watt sounded relieved that he didn't have to make that decision.

"I'm glad we didn't get to that point," he said.