Andrew Carlson has won national titles at two distances. He's represented the United States in six international competitions, including the world half marathon and cross-country championships.

Still, when he spoke with patrons at the south Minneapolis running store where he works, he discovered his résumé lacked one essential component in their eyes.

"You have no credibility with customers if you haven't run a marathon," Carlson said. "They don't care what you've done at any other distance."

He filled that void when he finished sixth in his marathon debut at last January's Olympic trials. Sunday, he will attempt to burnish his credentials by taking on one of the world's most famous races at the distance: the New York City Marathon.

Carlson, 30, is seeded 20th in a men's field that includes Olympic bronze medalist Wilson Kipsang of Kenya and top Americans Meb Keflezighi and Abdi Abdirahman.

Carlson long had contemplated moving up to the 26.2-mile distance, but the timing wasn't right until last year. While he initially was delighted with his finish at the trials -- and his time of 2 hours, 11 minutes, 24 seconds, the seventh-fastest debut by a U.S. runner -- coming so close to an Olympic berth left him second-guessing some decisions. Knowing what to expect has made Carlson eager to see what he can do in New York, where he will be part of a race expected to draw 47,000 runners.

"To have the feeling I've done this once, that's a good strength now," said Carlson, a former Gopher who won the U.S. 15-kilometer title in 2008 and the 25K title in 2010. "I cramped up in Houston [at the trials], and I'm not planning on that happening again.

"I'm trying this time to be as open as possible to something great happening. I'm beyond excited."

Preparation and strategy

At the U, where he ran both track and cross-country, Carlson set a school outdoor record in the 5,000 meters (13:44.64) and was a two-time All-America. Since turning pro at the end of his Gophers career in 2005, the Fargo, N.D., native has recorded top-10 finishes in U.S. championship events from the 5K to the marathon.

Carlson trained with many top-flight marathoners as a member of the Team USA Minnesota distance running group, learning about preparation and strategy from teammates such as Matt Gabrielson and Jason Lehmkuhle. Carlson originally planned to race the distance for the first time at last fall's Twin Cities Marathon, but an injury put his debut on hold.

He quickly shifted his focus to the Olympic trials in Houston, feeling confident that a lifetime of racing -- and all that knowledge he picked up from his training partners -- would serve him well.

While the leaders set a fast pace, Carlson and Lehmkuhle settled into a chase pack. They were less than 2 minutes behind at the 20-mile mark when Carlson felt his hamstrings tighten.

"In my mind, I pictured myself easily coasting through the last six miles," he said. "Then, all of a sudden, you go from 'This is easy' to 'This is the hardest thing I've ever done.' I didn't handle it all that well. I freaked out more than I should have."

Lehmkuhle fell back and finished 18th. Carlson hung tough, and while he was disappointed at not making the Olympic team, he was hooked on the distance.

Dennis Barker, coach of Team USA Minnesota, said Carlson was well-prepared to run fast that day -- and that he can run even faster.

"When Andrew is on, he's really on," Barker said. "That comes from something internal. On the right day, he can run 2:09."

Tuning up

Carlson has been running as much as 135 miles per week. The Olympic trials taught him to be constantly aware of everything within and around him -- because anything can happen during 26.2 miles -- without succumbing to the emotional swings that can play havoc with the mind.

In early October, Carlson tuned up for the race with a seventh-place finish in the U.S. 10-mile championships, run in conjunction with the Twin Cities Marathon. Though he will continue to compete at multiple distances, he said he feels like a marathoner now. That's given him a new connection with his customers -- and with the name on the awning -- at the store where he works, Marathon Sports.

"I really love to sink into the marathon training," he said. "It's when I feel best and most alive in running.

"I've been accepted into the fraternity. It's been fun to have some camaraderie I didn't have before."