Near the time of his achievement in the Met’s “Ring,” in which he managed to invest the faceless staging with vividness, he began little by little to curtail his opera engagements, particularly productions in the United States that sent him away from home in Wales for long stretches. This cleared time for more concerts, and special projects like a semi-staged “Sweeney Todd” alongside Emma Thompson that originated with the New York Philharmonic in 2014, then traveled to London.

Terfel was set to come back to the Met as Scarpia when its ornate current “Tosca” production, directed by David McVicar, opened in late 2017. But after arriving in New York to start rehearsals, he dropped out to have a polyp removed from his vocal cords. In early 2020, he was supposed to star in the Met’s first new staging in over three decades of Wagner’s “Der Fliegende Holländer,” but fell in Spain, broke his ankle and had to withdraw.

“He seemed to be cursed by the gods,” Gelb said.

Terfel appeared in one of the company’s pandemic-era video recitals, beaming in from a cathedral in Wales for a warmhearted holiday program in December 2020. But he was eager to return to the theater, even if it took a few more years before these “Tosca” performances could come together.

“I didn’t want it to end with a tri-tib break,” he said, referring to the triple fracture of his ankle that kept him out of “Holländer.”

Rehearsing at the Met last week, Terfel was walked through McVicar’s production, his blend of suavity and menace still potent. “You can play Scarpia with a smile on his face,” he said, “and then, of course, when people are not looking, that snarl can be very, very prominent.”

He stuck broadly to the blocking while constantly trying out new ideas, exploring the character and finding unexpected solutions to small challenges — like where Tosca’s left hand should go to distract him from the knife in her right.