PASADENA, Calif. — For Bruce Arena, the Los Angeles Galaxy’s coach, this season has been one of changes. More are coming. So Arena was in no mood Tuesday night to spend time breaking down the nuances of an exhibition game, even if it was a rare chance to test his team against the visiting European champion, Barcelona.

“It’s an exhibition,” he told reporters afterward. “Relax.”

Arena’s major concern, his only concern, is to mold the Galaxy into a unit that is able to repeat as Major League Soccer champion. He is doing it all while navigating three major transitions.

The first came in December, when Landon Donovan retired after leading the Galaxy to the M.L.S. Cup title. Donovan, the career leader in goals and assists in M.L.S., had spent 10 years with the club and won four of his six league championships with the team.

“You’re never going to replace a guy like that,” defender Todd Dunivant said. “He’s won six championships in this league. He’s set every record in the national team and in M.L.S. When you lose a guy like that, it’s going to change your team. You have to figure out ways to adapt.”