The two-time Pro Bowl defensive end was the first pick of the 2006 draft when selected by the Houston Texans, and became one of the best pass rushers around with 53 sacks and 241 tackles in his 82 career games.

A chest injury limited him to just five games last season, and the Texans seemed to get along fine without him so opted to allow him to enter free agency.

The 27-year-old was still the second-biggest free agent on the market behind Peyton Manning, and the reported $96 million the Bills have shelled out to get him shows that perfectly.

His deal could even reach the $100m mark with incentives, but Williams says it was the chance to turn things around in Buffalo which persuaded him to sign on the dotted line.

Big chance

"You don't get many chances like this and opportunities to come in and be the guy who can help the team get across the hump and that's definitely what I am here for," said Williams.

"My whole intention is to come here and make this thing happen. It' a great opportunity for myself and the team and for us to succeed and get better. This city is looking for that."

Buffalo started brilliantly last year, but their defence lacked a pass rush as they managed just 29 sacks and eventually finished 6-10 for the season.

Having defensive tackles Kyle Williams and Marcell Dareus playing inside him and being welcomed in Buffalo by legendary quarterback Jim Kelly during his stay also helped Williams make up his mind.

"It was huge," Williams said. "The biggest thing for a defensive end is... when you're getting around the edge, the quarterback not stepping up.

"I know that's what we have here. So that was one huge sell to me, was having those two guys pushing the pocket, and hopefully I get the sacks."

Recruitment

"Coming here and seeing (the Bills) embrace me and definitely the comfort level of everybody that surrounded me when I got here. Even Jim Kelly was definitely a big plus and he did some heavy recruiting."

The Bills feel they are very close to ending their 12-year play-off drought - they certainly looked like a play-off team at the start of last season - and just strengthening up on defence may just get them over the line.

Adding Williams will undoubtedly help with that, and Bills general manager Buddy Nix was openly excited about making the signing.

"It's an exciting day for us and for our football team, we got a lot better," said Nix.

"Once we got him here and got him to listen, not to people who have heard about Buffalo but the people who live here, then you find out what unique place it is and he's going to help it get even better."