NEW YORK — After more than half a century as an operatic powerhouse, Placido Domingo might easily take success for granted. Instead, each time he storms onstage as the ruthless ruler in Verdi’s “Nabucco,” he feels he has “more than ever to prove.”

“Because there are no excuses right now,” Domingo said. “I have made a long and beautiful career, and if I go out there it’s because I’m doing it well. Otherwise people will say, ‘Why is he doing it,’ you know?”

“So there is always a reason to have butterflies,” he added, in an interview at the Metropolitan Opera.

Domingo, who turns 76 this month, is enjoying a triumph in Verdi’s third opera, which tells the story of the Babylonian tyrant Nebuchadnezzar and his sacking of the temple of Jerusalem. The final performance will be broadcast to movie theaters worldwide live in HD on Saturday.