BUFFALO, N.Y. -- Buffalo Bills quarterback Josh Allen awoke at 3:45 a.m. Friday to a call from his agent, telling him a contract extension that would make him one of the highest-paid players in NFL history was basically done.

Allen's representatives, as well as Bills GM Brandon Beane and his front office, had been working on the final terms of the deal since 10 p.m. and had finally come close enough to officially loop Allen in on the progress.

Even with practice at 10 a.m. Friday, Allen shared the news with his girlfriend, brother and parents -- going back to bed could wait.

"As you can imagine, it was pretty hard to sleep after that," he said.

Allen and the Bills agreed to a six-year contract extension, the team announced Friday. The deal tops out at $258 million, with $150 million of that guaranteed, sources told ESPN's Adam Schefter.

According to ESPN Stats & Information research, the $150 million in guaranteed money is the most in a single contract in NFL history, surpassing Kansas City Chiefs star Patrick Mahomes, whose deal includes $141.5 million guaranteed. Allen's $43 million in average annual value is second to Mahomes' $45 million.

Allen, the No. 7 pick in 2018, had his fifth-year option picked up in May as a formality; both sides had previously expressed their desire for a long-term deal.

The length of Allen's deal, while not quite as long as Mahomes' 10-year extension, was meticulously chosen with the Bills' long-term success in mind.

"I think the way that we structured the deal was obviously a chance for both sides to get a fair deal and feel like they won," Allen said. "To be here for eight more years and allow us to kind of move some things around to keep some pieces here -- I'm not egotistical in how the money is put out or where it needs to be or how much it is. I want to win. Whatever it takes for us to win is what I'm willing to do.

"At the end of the day it's still a lot of money. As someone alluded to earlier, it's generational wealth and something to be super proud of. The ultimate goal for now is winning, and it's not going to matter if we don't win."

Beane told The Associated Press on Monday the two sides had agreed to set the first week of the regular season as a deadline to negotiate the deal or table the talks until next year.

While Allen's deal with the Bills comes as Baker Mayfield and Lamar Jackson remain in talks with the Cleveland Browns and Baltimore Ravens, respectively, Beane said there was no sense of urgency to make Allen the first quarterback in the 2018 class to sign an extension.

"I didn't really worry about those guys. I mean there's various ways to do it, various structures," Beane said. "I knew even last year -- Josh and I had an off-the-cuff conversation about doing a deal, with him wanting to make sure he could do a deal that took care of him and his family, but that we could still win around here. So I took all that into consideration as we structured this thing.

"I really wasn't worried about other deals, whether they happened or not. It was about getting the right deal for Josh and the right deal for the Buffalo Bills. And I believe that's what happened."

Allen earned the extension after an MVP runner-up season in 2020. He set franchise records for passing yards (4,544) and passing touchdowns (37) and led the Bills to the AFC Championship Game and their first division title since 1995.

He made noteworthy improvements from 2019 to 2020, increasing his completion percentage from 58.8% to 69.2% and his passer rating from 85.3 to 107.2. Allen also was named to his first Pro Bowl.

While his meteoric rise to the upper echelon of NFL quarterbacks came as a surprise to fans and pundits across the league, it wasn't surprising to anyone inside the building. Beane said he knew "very early on" that Allen was worthy of a long-term extension, and head coach Sean McDermott said Allen didn't necessarily prove anything in 2020 that he hadn't already proved to them the year before.

"When you're around people every day, it's just a continual evolution of a player in this case and a person," McDermott said. "So you don't see the real drastic changes, but you see the incremental changes day-to-day. ... It's obviously a leap of faith on our part and Josh's part as well. But the trust that has been built between the parties and then also just the belief that he's only going to continue to improve the way he's wired, the family he comes from, the support he has, the way his teammates view him -- that was all big in terms of doing it now and feeling good about it for the future as well."

Allen said he doesn't feel any additional pressure to live up to the dollar amount, saying he holds himself to a higher standard than anyone else ever could, but he does feel a responsibility to prove why the Bills drafted him -- a responsibility he has felt since they made him the franchise's highest-drafted quarterback ever in 2018.

And as statistically significant as his 2020 season was, that's not what Allen believes his new extension was built around.

"I know they didn't pay me for what I've done," he said. "They did this because they expect me to continue what I'm doing, and expect me to go win this team some championships.

"We've got a lot of work to do. I know that. And I'm just excited to put this behind me and start focusing on football now."