Mario Williams has agreed to join the Buffalo Bills for the richest contract given a defensive player in NFL history.

The linebacker-end who spent his first six seasons in Houston after being chosen No. 1 in the 2006 draft, got a six-year deal Thursday worth as much as $100 million, with $50 million guaranteed.

One day after Lions wide receiver Calvin Johnson got the biggest contract in league history — $132 million for eight years, with $60 million guaranteed — Williams scored his monster deal.

Earlier Thursday, guard Ben Grubbs agreed on a five-year, $36 million contract with New Orleans, where he will replace All-Pro Carl Nicks, who left the previous day for NFC South rival Tampa Bay.

Defensive end Frostee Rucker left Cincinnati for Cleveland and a five-year, $21 million contract.

Carl Nicks

right. has become the first 2011 All-Pro to change teams in free agency

Marcio Jose Sanchez

leaving New Orleans on Wednesday for the Tampa Bay Buccaneers. (ASSOCIATED PRESS)

Lynne Sladky