Adrian Peterson turned 30 in March. The milestone birthday, by NFL standards, automatically sparked questions about his durability and long-term value. Nine-plus months later, he's on the verge of becoming only the second player 30 years or older to win an NFL rushing title.

"The eight years I've actually played full seasons, I've always envisioned winning and leading the league in rushing," Peterson said. "So it wasn't any different coming into the season. I think people add more to it because of everything that took place last year and people saying this about my age and so forth.

"For me, it's something that I expected to accomplish each year."

Peterson holds a 64-yard lead over Tampa Bay's Doug Martin entering the final week of the regular season. With the Vikings slotted for the final NFL game on Sunday, a showdown at Green Bay for the NFC North title, Peterson will know how many yards he needs to secure his third rushing crown when the game begins.

In his ninth season, Peterson has 1,418 yards on 308 carries. He's averaging 4.6 yards per carry and 94.5 yards per game and has 10 touchdowns. Martin, Peterson's only challenger, has 1,354 yards on 273 carries. He is averaging 5 yards per run and 90.3 per game and has six touchdowns.

Once the questioning shifted to a third rushing title on Thursday at Winter Park, Peterson couldn't hold back a big smile.

"Of course" the rushing title matters, Peterson said. "I'll have the opportunity to do that this weekend. It's not something that I'm trying to focus on too much. [But] of course I'm going to go out and always put my best foot forward.

"I get a little advantage. I'll know exactly what I need going into the game, so that's a perk."

Peterson won his first rushing title at 23 years old in 2008 with 1,760 yards. Four years later, he won his second with 2,097 yards, 8 shy of Eric Dickerson's single-season record of 2,105.

For now, Hall of Fame running back Curtis Martin is the only thirty-something to win the title, gaining 1,697 yards at age 31 for the New York Jets in 2004.

"I've paid attention to it a little bit and sit back and how I think 'Wow, I can't believe that [it's only been done by one other 30-year-old],' " Peterson said. "It's hard for me to believe because I see myself having the opportunity to win it a couple more years. It will be special to join that group."

Peterson's yardage this season is ninth best by a 30-or-older player.

Leading to last week's 49-17 victory over the New York Giants, visiting coach Tom Coughlin said Peterson looks like he's 25 years old again. Coughlin lauded Peterson's quickness, his power and said he looked well-rested; Peterson responded by rushing for 104 yards and a touchdown while spending most of the fourth quarter resting on the sideline.

"He's been the same player ever since I got here five years ago," said Vikings guard Brandon Fusco, one of the linemen to receive a snowmobile as a gift from Peterson after he won the rushing title in 2012. "He's a hard worker and takes care of his body.

"He's a physical, crazy, freak player."

Peterson won his last rushing title a year after tearing the ACL in his left knee and capped the comeback year with a win against rival Green Bay to earn a spot in the postseason. He's made the most of another comeback opportunity after missing most of the 2014 season and will eye another big performance in another season finale against the Packers.

"I like turning people into believers," Peterson said. "Even when I win, people will still doubt me. That's just the way of life. You got people that believe, you've got people that doubt you and say this, say that. That's the way of the world. You just have to stay in your lane and do what you do."

The last time Peterson was running for a rushing title against the Packers, he finished with 199 yards. He likely won't need anywhere near that total this time, but with the division championship on the line, expect Peterson to carry a heavy load as the Vikings aim for their first NFC North title since 2009.