There’s one certainty as the United States men’s basketball team navigated through its five-game exhibition tour undefeated: LeBron James is the closer.

The four-time NBA MVP and two-time gold medalist has carried Team USA in the fourth quarter of its past two games, late wins against South Sudan and Germany. The Americans will open Group C play Sunday, 28 July against Serbia and its exhibition games have been arduous learning experiences.

Team USA won its past two games by a combined five points, with James making key buckets late each time, including a pivotal three-pointer to overcome the Germans, who led going into the fourth quarter. James, 39, has been Team USA’s best player during the exhibition schedule, returning after a 12-year absence.

After the game, James warned his teammates about being complacent because of their immense talent. Meanwhile, Kevin Durant, the former MVP and one of the more prolific scorers in the world, has yet to play and could make his debut Sunday against Serbia.

While there were predictions that the Americans would coast through the Olympic tournament with a roster that has 11 NBA All-Stars, four MVPs and arguably the best player to ever play the game (James) and the best shooter (Steph Curry), the exhibition stretch indicated that opponents aren’t daunted by Team USA’s talent and it is vulnerable when lackadaisical play becomes an issue.

“I’ve learned we’re beatable if we don’t execute the details of what teams know they have to do to beat us,” Curry said via USA Basketball’s Instagram page. “Which is extra possessions, not taking care of the ball, fouling too much. It has nothing to do with our offensive game. Obviously, Bron has been taking over in the fourth quarter, giving us a huge bump but we haven’t played our best offensive game yet.

“When we lock in defensively and rebound, nobody can really beat us. That’s how we’ve been coming back these last two games. Just execute the details and playing solid, hard-nosed basketball, we’ll be fine.”