KANSAS CITY, Mo. – They came into MLS together, lived under the same roof for a while as rookies with the Kansas City Wizards and won a couple of trophies together with the rebranded Sporting Kansas City. Now, Matt Besler and Graham Zusi are one step away from being World Cup teammates in Brazil.

Neither one is taking that last step for granted, even though both have become mainstays for the U.S. national team – Zusi in the midfield and Besler on the left side of central defense.

“I don't think that either of us knows that we're going to be mainstays for years to come, or even for this tournament,” Zusi said at a news conference on Monday, shortly after U.S. coach Jurgen Klinsmann announced his 30-man preliminary roster. “That's not the way I think, and I don't think it's the way Matt does as well.

VIDEO: Raising Zusi

“I think we're going to this pre-camp the same as every person on that roster,” he went on. “They want to make the final roster. They're going to do whatever they can to make that final roster. I don't allow myself to think that far ahead, I guess, to solidify myself in the XI on the field right now. I think there's just way too much work to be done.”

Besler, the anchor of the league's stingiest defense in 2012 and 2013 – and so far this year as well – agreed with his teammate's assessment.

“The mentality really doesn't change at all,” he said. “You have to prove yourself every single day – in practice, in camps. It doesn't matter who you are. I think Jurgen's proved that, with some of the guys on the team. If you look at a guy like Landon (Donovan), arguably our best player in U.S. history, he has to prove himself every day, just like anyone else on the team. That's the mentality.”

The two, who will play in Sporting KC's home match against Philadelphia on Wednesday and then join the national team the next day, were drafted in 2009 by the then-Wizards. In that first season, they both lived with Besler's family in suburban Overland Park, Kansas.

Zusi made his national team debut in 2012, the year Sporting won the U.S. Open Cup for the first time since 2004. Besler broke into Klinsmann's lineup last year, quickly becoming a fixture in central defense, and the two capped their shared success in 2013 by helping Sporting take their first MLS Cup title since 2000.

“To go through all the steps that we have pretty much simultaneously – progressed together, became important figures for our club team – and then to take the next step to the national team, is something you don't see very often,” Zusi said. “It's been a great journey for myself and for Matt. It's just fun to have a familiar face there at all times, and a friend that you can either bounce stuff off of or just experience things together.”

There's another benefit to their relationship as friends and teammates as well, Besler said.

“I think neither of us have ever admitted it to each other, and neither of us really will admit it, but I think that we're competitive with each other in a very positive way,” he said. “And through this whole professional career that we've had together, these six years so far, I think we've pushed each other along the way very silently. We've been there for each other.”

Steve Brisendine covers Sporting Kansas City for MLSsoccer.com.