LAS VEGAS — A few hours before he would face the most important test of his international playing career, Trail Blazers All-Star Damian Lillard decided he needed a workout.

So on Sunday night, the evening before the start of the USA Basketball training camp, he met a friend in the lobby of their Las Vegas hotel and headed over to the Mendenhall Center for a rigorous session of individual drills, shooting and highly competitive games of one-on-one.

Lillard's playing partner that night: Cleveland Cavaliers point guard Kyrie Irving.

As they have competed against each other in USA Basketball camps the last two summers — first on the Select Team and now on the National Team — two of the NBA's best and brightest young stars have blossomed from rivals into friends. They play perhaps the deepest position in the NBA and are part of the most intense and spirited competition at this week's training camp.

And when it's all said and done next month, with Derrick Rose developing into a near-lock and Stephen Curry strengthening his chances every day, the final guard spot on the USA's 12-man roster at next month's FIBA World Cup may come down to one of the two burgeoning friends.

It's a fitting situation for a unique relationship.

"We always want to get the best out of each other," Irving said. "Off the court, we're great friends. But on the court, we want to rip each other's hearts out."

USA Basketball fuels friendship

Their friendship has been in the making since Lillard joined the NBA during the 2012-13 season, but mostly has been nurtured through their competition in USA Basketball. They exchanged phone numbers during Lillard's rookie season and Lillard reached out later that year, texting Irving before the All-Star game to congratulate him on his first berth. A few months later, Irving returned the favor, texting Lillard to congratulate him on being named the NBA's Rookie of the Year.

Lillard has long been an admirer of Irving's game and while he has formed close bonds with other rivals across the NBA — most notably Washington Wizards point guard John Wall — Lillard holds a particular affinity for Irving because of the similarities in their career arcs. Irving entered the NBA one year before Lillard and has established a high level of success that Lillard has been chasing — successfully — ever since.

Irving was named NBA Rookie of the Year after his first season. So was Lillard. Irving became an All-Star during his second season. So did Lillard. Both are franchise-changing point guards who have carried their teams from Day 1, and both have put up near-identical statistics in their young careers. Lillard holds career averages of 19.9 points, 6.0 assists and 3.3 rebounds; Irving holds career averages of 20.7 points, 5.8 assists and 3.7 rebounds.

"Our careers are kind of on the same trajectory," Lillard said. "And we have a respect for each other."

Last summer, their friendship received a jolt when they played together on the Select Team in Las Vegas. They split time excelling alongside each other and competing on opposing teams during the mini-camp and quickly discovered they shared a host of similarities. Both are maniacal workers. Both are supremely competitive. And both remain humble, despite their young celebrity.

When they weren't going toe-to-toe on the court, they conferred off of it. In Irving, Lillard saw both a guide for where he wanted to be and a mentor.

"It was the first time that we actually had to be around each other for a week and talk every day," Lillard said. "The way his career was going, I wanted that for myself — him being an All-Star in his second season. I told him I wanted the same thing, so we talked about how he did that. He just told me how huge the summer was going to be ... because it's your opportunity to grow and you've got to be willing to take that huge step and make those sacrifices.

"For somebody that's accomplished so much, he's so humble. He's a chill dude ... always laughing and always joking. And it's just so natural. He lightens the mood all the time."

Lillard and Irving kept in touch after their Select Team commitment ended. When the Blazers visited Cleveland in December, Irving met Lillard for dinner. The next month, when the Cavaliers stopped through Portland, Lillard met Irving for dinner. After Lillard hit that series-clinching three-pointer to deliver the Blazers a first-round playoff victory over the Houston Rockets, Irving was one of the many to text and congratulate him. And earlier this month, when Lillard learned the Cavaliers had stunningly signed LeBron James, he instantly texted Irving.

"I said, 'So, y'all going to the finals, huh?'" Lillard said, chuckling, as he recalled the moment. "He was like, 'Chill, chill.' We joked about it."

Generational point guards

One thing they don't joke about is their standing in the league and their career ambitions. Both aspire to be the best point guards in the game and both fiercely want to win. They respect each other's competitive nature and otherworldly talent. But that only makes them want to beat each other more.

"We're generational point guards," Irving said. "Obviously, he wants to be known as the best point guard for our generation. I want to be known as the best point guard. That's what you look forward to as competitors. It's exciting. It's nothing personal. It's what we want to be remembered as, what we want our legacies to be. That's what it's about. But when we compete, we want to get the best out of each other. And we want to play better than the other person."

And in that column, Lillard has the upper hand so far. During the three games they have faced each other, the Blazers are 2-1 and Lillard has enjoyed memorable performances in the wins, including a 36-point, 10-assist, eight-rebound explosion in Cleveland last season. During that game, Lillard made 11 of 23 shots, including 8 of 12 three-pointers, and hit the game-winning jumper with 0.4 seconds left — his second game-winner in a row.

What's more, while Lillard became a playoff hero in just his second NBA season, Irving has never reached the postseason.

But it's early in their playing careers and there are bound to be a surplus of unforgettable head-to-head matchups between them in the future. Irving signed a maximum contract extension with the Cavaliers this summer and the addition of James instantly makes the Cavaliers a contender in the Eastern Conference. Lillard had his first taste of playoff basketball last season and the Blazers appear to be a team on the rise.

Competing on Team USA planted the seed for rivals to become friends and that bond will likely only strengthen as they continue to establish themselves as NBA stars.

"You become friends with guys that you see have the ability to play this game, with guys that you respect," Irving said. "Obviously, we play the same position, we both have our own individual accomplishments and ... we share a common goal and same chip on our shoulders. I don't think everybody believed we were going to be who we have become in such a short time. But we have and that, in a way, has helped us form a friendship."

--Joe Freeman | @BlazerFreeman