The Arizona Cardinals' Patrick Peterson, in the discussion as the NFL's top cornerback, received a five-year extension worth $70 million, he announced on Twitter on Tuesday night. The team followed with an official announcement, although it did not release terms.

Peterson, a Pro Bowl player in each of his first three seasons, including as a returner as a rookie, wrote that $48 million of the contract is guaranteed.

"Do I feel I'm the best cornerback? Absolutely," Peterson said at the beginning of training camp. "That answer is never going to change."

Seattle Seahawks cornerback Richard Sherman signed a four-year, $57 million contract in May, with $40 million guaranteed.

Peterson, 24, will be able to focus solely on his defense this season. Cardinals coach Bruce Arians said the team won't use Peterson on punt returns or on offense, where he dabbled last season because of his speed, getting 11 touches.

Peterson (6-1, 219) has 12 career interceptions, including three last season, when he made 42 tackles. He has four punt return touchdowns, all during his rookie season of 2011. He is one of seven players to be selected to the Pro Bowl three times before his 24th birthday.