NEW ORLEANS — One is a country boy from rural Missouri his teammates call Cowboy. The other is the city kid from Raytown now better known as the San Francisco 49ers MVP.

Together, San Francisco 49ers defensive end Justin Smith, in his 12th NFL season from Missouri, and outside linebacker Aldon Smith, in his second year from Mizzou, have formed the most feared 1-2 punch in the NFL.

Though Super Bowl XLVII will be known for the historic matchup of head coaching brothers in San Francisco’s Jim Harbaugh and his brother, Baltimore coach John Harbaugh, another pair of namesakes could dominate Sunday’s game.

“Well, the ‘Smith brothers,’ ” John Harbaugh said, “They’re related by their greatness.”

Jim Harbaugh took it a step further in describing Justin Smith, who a year ago was the first player to be voted All-Pro at two different positions the same year, defensive tackle and end.

“Justin Smith is one of the greatest players ever to play in the National Football League,” said Harbaugh, who played with the likes of Walter Payton while with the Chicago Bears. “He’s the kind of player every team should have.”

While Aldon Smith led the NFC in sacks with a franchise-record 19 1/2 this season, and Justin was voted to his fourth straight Pro Bowl, there were some concerns about their effectiveness late in the season. Justin Smith, who had played in 185 consecutive games, suffered a partially torn triceps on Dec. 16 at New England.

He sat out the last two games of the regular season and played with a bulky brace in the playoff wins over Green Bay and Atlanta, but Aldon Smith failed to net a sack in any of those games.

“Justin not being in there plays a part in that,” Jim Harbaugh said. “But the play of Aldon has been really good. Aldon got a game ball from our team off his performance in the (NFC championship game). He had a number of pressures and hurries … he recovered a fumble and had a thorough, good game. Even though he didn’t have the sacks there … he played at a high level.”

The Smiths are two of the three highest-draft picks out of the University of Missouri. Justin, who set the Missouri single-season sack record with 10 in 2000, and was the fourth overall pick by Cincinnati in 2001, matching Russ Washington, who was taken fourth by San Diego in 1968. Aldon Smith, who broke Justin’s school record with 11 1/2 sacks in 2010, was the seventh overall pick by the 49ers in 2011.

“It’s definitely cool with two guys coming from Missouri, but we’re playing for San Francisco now,” said Justin Smith, 33. “He’s setting records left and right, so I think anytime anybody does that it’s surprising. Just his transition into the NFL and how easy he’s made it look, that’s what the great ones do — they make it look easy.”

Justin Smith developed his indefatigable work ethic growing up on a cattle ranch, performing chores until everyone else dropped.

“That’s all I knew,” he said of the ranch. “I don’t know how it would be to grow up any other way, honestly.”

Smith took that energy into the weight room and onto the football field. He never missed a practice at Jefferson City High School, at Missouri, or in his first 11 NFL seasons until the recent triceps injury.

“In high school there were kids around him who tried to challenge him,” Jefferson City coach Ted LePage said. “In the weight room, ‘Could you put 10 more pounds on the bar …?’ Or on the field, ‘Could you run that guy down?’ … He would always rise up to the challenge. Even though he was better, bigger, stronger, faster, he always wanted to do that next thing. Anybody challenge him, ‘OK, here we go.’ ”

San Francisco offensive guard/tackle Alex Boone absolutely hates practicing against Smith, a powerful 6-4, 285 pounds, who has 75 1/2 career sacks.

“It’s an eye-opener,” Boone said. “The guy will rip you apart. He’ll do it again over and over. I feel like I’ve grown so much in this league by understanding football through his eyes. He tells me all the time, ‘Don’t ever do the same thing the whole game. They have to be thinking just as much as you are. It’s helped me tremendously.”

Because of his durability, Smith didn’t know how to react when he suffered the triceps injury at New England.

“The first thing that went through my mind was, ‘What the (heck) did I do?’ ” he said. “I have never felt a pop like that before. The doctors were pretty confident that if it progressed right, that I’d be ready to play. It worked out that way, so you just keep going as long as you can.”

The timing of the injury could have been devastating for Smith, who had reached the playoffs just twice in his career, including last year when the 49ers lost in overtime to the New York Giants in the NFC championship game.

“I’ve never been that close (to a Super Bowl) in my life,” he said. “You don’t think it’s over or your window is closed or anything like that just personally speaking, and you feel it kind of shutting. I was just like, ‘Damn, that was it.’

“To be back in the NFC championship game, I don’t think our team took it as much for granted how hard it is to get there. Getting to the Super Bowl, now especially, you have to take advantage of it.”

Aldon Smith dropped on Raytown’s door step after moving from Cedar Rapids, Iowa, between his sophomore and junior years in high school. He fancied himself more as a basketball player until Raytown High School football coach Ken Clemens got hold of him.

“The first time I ever met him, his dad brought him out to a 7-on-7 game we were playing out at Fort Osage,” said Clemens, now the head coach at Liberty North. “I’m kind of prone to hyperbole when I get excited about a kid, and I told my whole staff, this kid is a Division I football player.

“You shake his hand, you know he’s passed the eye test and he got out there and ran … and it was more than obvious that he was put together a little differently than most.”

The NFL was embroiled in a lockout in 2011, preventing Aldon Smith from reporting to camp and learning the 49ers defense. But Justin Smith invited his fellow Mizzou alum to the club’s off-season workouts at San Jose State.

“From the time I stepped into the NFL, he helped me with everything,” Aldon said. “And on the field, we work well together. We feed off each other, and have a rhythm we developed together.”

Smith, a rangy 6-foot-4, 258 pounds, was an immediate sensation. He registered 14 sacks as a rookie, falling a half sack shy of the NFL rookie record set by Jevon Kearse in 1999. And his 33 1/2 career sacks are an NFL record for a player in his first two seasons.

But with success come some perils. Last January during Super Bowl week, Smith was arrested for DUI in Miami Beach. And last summer, he suffered “minor injuries” when involved in an stabbing incident at a house party near San Jose.

Smith, 23, chalks it up to a learning experience.

“You’ve got to make better decisions, really,” Smith said. “I’ve kept my goals in mind and the guy I want to be and the great player I want to be and how I want to be viewed. I’m a football player who works hard, and I want everybody to know that.”