SANTA CLARA, Calif. -- As the clock ticked into the late hours of March 16, offensive tackle Trent Williams was growing more and more convinced that his first foray into free agency was going to lead him away from the San Francisco 49ers and to the Kansas City Chiefs.

Williams had long maintained that he wanted to stay in San Francisco with coach Kyle Shanahan, but momentum toward a new deal had stalled and the Chiefs were making what he called Tuesday a "good push."

But Williams, who has known Shanahan since their time together in Washington in 2010, had told Shanahan before free agency started that he wouldn't leave without giving Shanahan a final chance.

"Once I got the hunch that K.C. seemed like they were ready to make it official, I called Kyle," Williams said Tuesday. "I couldn't even get it out and just tell him, but I was just like, 'Hey man, we need to hurry this up, if you get my drift.'"

Williams' message to Shanahan was actually sent by text, and the drift was simple: If something didn't happen soon, he was on his way to Kansas City.

Shanahan immediately called Williams, who was walking into James Harden's new restaurant, Thirteen, in Houston when Shanahan reached out. Williams stepped outside to speak to Shanahan and let him know that he was planning to make his decision by the time his dinner was over.

Before Williams got his keys from the valet little more than an hour later, Vincent Taylor, Williams' agent, called with the news that Williams was staying in San Francisco on a record-setting six-year, $138 million deal with $55.1 million in guarantees.

It was the culmination of a two-year journey in which Williams sat out the 2019 season because of a rare form of cancer and a dispute with Washington over the handling of his injuries and his contract.

In the months leading up to free agency, Williams had maintained that he wanted to test his value -- something made possible by a contract stipulation that he couldn't be franchise tagged -- and wanted to remain in San Francisco.

Despite all of that, Williams wasn't sure he'd be able to make both things happen as he received recruiting messages from the likes of Chiefs quarterback Patrick Mahomes and Indianapolis Colts guard Quenton Nelson.

"I thought I would either get a lot of money and be somewhere I hated to be or I would be somewhere I love to be playing for a discount," Williams said. "I definitely didn't think it would be both."

Williams' comfort level with the 49ers, and especially Shanahan, was evident from the time the team traded for him on the third day of last year's NFL draft. The 49ers felt the same way about him.

"After a year away from the football field, Trent came in and performed at an incredibly high level for us, demonstrating that he remains an elite tackle in this league," general manager John Lynch said in a statement announcing the signing. "His familiarity with our coaching staff allowed for a seamless transition into our organization and culture, where he quickly earned the trust of his teammates and established himself as an important leader in our locker room. Trent's passion for the game could be felt from Day 1 and this fits exactly with our vision of the 49er way and a championship culture. His contributions to our team extend well beyond the field and we're thrilled to keep Trent in the Bay Area for a long time."

Williams has said Shanahan's offense has a way of showcasing his unique combination of size, strength and athleticism and that there's an inherent trust that goes with knowing the Shanahan family for so long.

In fact, Williams said he was in Cabo San Lucas, Mexico, with Shanahan's father, Mike, just before free agency began and the subject of free agency never even came up. No sales pitch from any member of the Shanahan family was necessary.

"Kyle is like family to me," Williams said. "His family is like family to me. ... That's just how close I am with that family. Kyle didn't have to sell anything to me. I already knew what this place has to offer. I knew what he has to offer, and I knew what the front office would have to offer."

As it turned out, once the front office offered the largest contract for an offensive lineman in NFL history, the deal was done. Soon after it was, Shanahan messaged Williams and told him to "go get" the sixth year of his deal, the implication being that the 32-year old Williams has a chance to show he can stay an elite tackle deep into his contract and his 30s. Possibly even his 40s.

"I think playing until 40 is well within reach," Williams said. "The way I feel right now, I do think I have six years in my body. But I'm not going to be unrealistic. I'll take it one day at a time and continue to plug away at it, but that is the goal. I have something to prove. Can I play at a high level until I'm 40? We'll see."