James Harden was going up for a layup. Paul George was going up to contest the shot. When they came down, George had broken his leg and Harden had to look on, petrified and perplexed by what transpired.

“That was tough,” said Harden, who struggled to watch as George agonized near the basket stanchion.

The unfortunate, seemingly innocuous sequence in a nationally-televised Team USA scrimmage earlier this month set off a short-lived debate about NBA stars participating in international basketball, forced George into a lengthy recovery process and inadvertently thrust Harden into a role that the Houston Rockets all-star guard hadn’t foreseen when USA Basketball first announced its 28-man tryout pool for the FIBA World Cup last January.

Harden’s responsibilities increased once more when Kevin Durant, his close friend and former Oklahoma City Thunder teammate, backed out of his commitment, citing fatigue and not the injury to George as the reason. That left the lefty Harden as the only first-team all-NBA player remaining on the squad. The earlier withdrawals of Kevin Love and Russell Westbrook also meant that Harden and Anthony Davis were the only holdovers from the 2012 London Olympics team.

“Right now, I think I would look to Harden as that leader,” USA Basketball chairman Jerry Colangelo said as his team continues to prepare for the tournament in which the winner earns an automatic berth in the 2016 Olympics in Rio de Janeiro. “Harden is kind of a natural leader and he seems to be willing to accept that role. And you can just kind of feel it and sense. He’s the one.”

The United States will open the FIBA World Cup on Saturday against Finland in Bilbao, Spain, and Harden is excited to be looked upon for more than he was in 2012, when he played the second-fewest minutes of any player on the gold medal-winning unit.

Harden’s career changed dramatically after that summer as Oklahoma City traded the then-sixth man of the year to the Rockets. He became an all-star in his first season, playing so well that Dwight Howard forfeited a bigger pay day from the Los Angeles Lakers to join forces with him in Houston a year later. The constant adjustments have been so common for Harden that the steadily-evolving situation with Team USA over the past few weeks feels almost normal for him.

“It’s so many things these last couple of years that’s been thrown at me, from me being traded, to people talking, just everything,” Harden said. “I try to focus on myself and how can I be a better basketball player. It’s still basketball at the end of the day. I try to do it to the best of my ability and continue to work hard.”

Harden declared himself as the best player alive two weeks ago, expressing a sentiment that was neither delusional nor particularly serious. But it represented a mindset that is required for elite-level basketball players – especially one with obvious deficiencies on the defensive end who also happened to be a viable candidate for league most valuable player last season. When pressed about that opinion, Harden didn’t backtrack.

“I think everybody feels that way. Every NBA player. Even growing up, growing up youngins have dreams that they want to be the best basketball players in the world,” Harden said. “As a basketball player, or any athlete, you got to have confidence, you’ve got to have confidence the whole time. You just go out there and do your job and have confidence that your abilities are good enough. Whatever is thrown at me, I just try to take it for what it is and just have fun.”

This offseason presented a new set of challenges for Harden and his NBA employer. Houston failed in attempts to lure Carmelo Anthony and Chris Bosh, couldn’t get a face-to-face with LeBron James, lost promising forward Chandler Parsons to in-state rival Dallas, traded Jeremy Lin and Omer Asik for what amounted to cap space and had to settle for bringing back Trevor Ariza as its major move.

The clumsy summer – which included a minor dustup with Parsons and another mild controversy about which teammates Harden chose not to dine with last season — also raised questions about whether Harden and Howard were a solid enough foundation during an era in which James has shown that players can serve as destinations as much as cities for star players. Harden disputed the notion that the Rockets had taken a step backward in a Western Conference that remains immensely competitive.

“I don’t even listen to it,” Harden said of the comments about his team. “I just try to focus on myself individually and our team and how can we get better. I’ll leave that up to everybody else to talk about it. All I can control is what we have in that locker and those guys, we’re going to go to war.”

Harden accepted blame for the Rockets’ six-game flameout against Portland in the first round of the playoffs. He averaged a team-best 26.8 points but is eager to redeem himself after shooting a miserable 37.6 percent from the field.

“I’m definitely motivated,” Harden said after coming up short in the playoffs. “Everything is a learning experience for me. I’m trying to do my best to not let that happen again. I put that on myself, just playing bad and not really carrying the team like I needed to do.”

On Team USA, Harden won’t have to carry the team with so many other talented scorers such as Stephen Curry, Kyrie Irving and Anthony Davis but he knows there will be times when he will have to take it to the cup with his hop-step drives or step back and drill a few three-pointers. Surprisingly, Harden has earned praise from Coach Mike Krzyzewksi for his effort on defense, an end of the floor where he was so uninterested that a YouTube clip of his foibles making an honest effort caught steam last season. He has no choice on this team.

“First of all, you got the top players in the world on your team, so if you’re not focused and locked in on defense, they are going to embarrass you,” Harden said. “I think our coach has done a phenomenal job of making sure we’re keyed in. [Chicago Bulls Coach and Team USA assistant Tom] Thibodeau is phenomenal with that defensive presence, so all those things collectively is why I’m so locked in.”

Colangelo said Harden has been one of the team’s most vocal players and has helped elevate practices with his effort and tenacity.

“I don’t know if he’s been waiting [to lead]. It’s evolved,” Colangelo said. “He came in as a pretty high draft pick. Got off to a great start in Oklahoma City. Whether he was disappointed or surprised by what transpired, he found himself in another uniform and that’s part of life in pro sports and the NBA, and I think he’s adjusted to that and his numbers get bigger and he’s being recognized more and more as the player he is. And this is a great platform for him to come out as a leader.”

After the final two practices in Las Vegas, Harden engaged in some spirited one-on-one battles with George and Durant that were so entertaining that teammates and coaches grabbed seats to watch. Harden said he has spoken to George “a couple of times” since the injury and expects him to “bounce back strong.” Last week in New York, Harden also had a chance to spend some time with Durant at a function for console game NBA2K15 and a charity basketball game at Barclays Center. Though those players aren’t around, Harden still has confidence that USA Basketball can keep alive a winning streak in international competitions that currently stands at 36, dating back to a semifinal loss to Greece in 2006.

“It gives other guys opportunities to showcase their talents,” Harden said. “Those guys dropped out or are not playing, but you still have other all-stars. We’re rolling with what we got and this is going to be enough.

“This is a different platform,” Harden said. “A platform that I haven’t really been on before, but I think most of us haven’t been on it, either. I think we’re all kind of figuring it out together. That’s what’s going to be so special about this team. We figure it out together and we come out with a gold medal, it makes it that much more special.”