NAPA, Calif. -- Four years ago, when he was on the Arizona Cardinals' practice squad, Ricky Lumpkin stayed at the home of fellow defensive lineman Dan Williams as he acclimated to the NFL.

Fast forward four years, Lumpkin returned the favor, allowing Williams to stay at his Bay Area home as Williams adjusted after signing with the Oakland Raiders as a free agent.

"We started at as teammates, but now we're brothers," Lumpkin said of his relationship with Williams. "It's great to be back with him."

Williams said when considering where to go in free agency, the idea of reuniting with Lumpkin played a role.

"It was an added bonus to be back with Lumpy," Williams said.

The two players are not similar in NFL terms. Williams was a first-round pick. Lumpkin went undrafted. Williams is now averaging $8 million a year with the Raiders, while Lumpkin is trying to make sure he stays on the 53-man roster. But there is an unwavering bond.

"It's been that way since my first day in Arizona," Lumpkin said.

The first thing Williams said to Lumpkin was to remind him that it was him who blocked the game-winning field-goal attempt when Tennessee beat Lumpkin and Kentucky.

Soon, the two were spending most of their time together. Williams said they spend much of their time playing video games together and he relishes the fact that Lumpkin "is a bigger nerd than I am."

Williams was one of Lumpkin's best men at his wedding and was in charge of holding Lumpkin's wife's ring during the ceremony. Lumpkin recently became a father. Williams considers Lumpkin's daughter his niece.

"My wife calls us twins," Lumpkin said. "We always used to dress the same in Arizona without planning it ... . Two weeks ago, sure enough he came over to my house wearing white shorts and a black shirt. What was I wearing? White shorts with a black shirt. ... It's good to have my twin back with me."