“All of Siam is here.” So said one of the actors of The King and I this past Thursday morning as we sat in the orchestra of the Metropolitan Opera, waiting for the dress rehearsal of Otello to begin. A quorum of the cast had assembled to watch the full-dress run-through of Verdi’s version of the Moor’s tale, which opens the Met’s season this Monday, September 21st.

Though I am sure there are devout opera lovers in the ensemble, most of the actors said they turned out primarily in support of their King and I director, Bartlett Sher. Sher was in constant motion throughout the rehearsal, racing between the worktables scattered throughout the orchestra seats, where tech types were buzzing away; to the lip of the orchestra pit, where maestro Yannick Nezet-Seguin was attacking the score with Verdian verve; to the stage proper, to give direction to a small band of musicians.

At the rehearsal’s intermission, Sher even found time to mingle briefly with some of the “King” and non-“King” performers who work on most regular Met nights and so could not see Sher’s latest handiwork otherwise. This band of Sher loyalists was almost as glam a crew as the society types who will be in attendance at the official opening Monday. There was Matthew (The Light in the Piazza, South Pacific) Morrison, currently starring in Finding Neverland on Broadway, and, I like to remind him, having the same birthday as I do. He chatted with his Piazza/Pacific costar, Kelli O’Hara, who wore a jaunty cap and looked very at home at the Met, having made her debut there this past winter in The Merry Widow.

Also spied: Jonathan Groff, on Broadway right now and stealing scenes nightly as King George III in Hamilton. He sat right next to me at Otello, and at first I racked my brain, wondering why he had showed up. Did he know any of the opera’s leads? Unlikely, as Sonya Yoncheva (Desdemona) is Bulgarian, Alexsandrs Antonenko (Otello) is Latvian, and Zeljko Lucic (Iago) is Serbian. (Like professional tennis, high-level opera seems dominated these days by eastern Europeans and Balkanites.) Was Groff a secret opera buff? It’s possible: he grew up in Lancaster, Pennsylvania, and performed as a teen at Lancaster’s Fulton Opera House. Or is he just a general music lover, looking for some edification on a non-matinee day?

As the lights went down on the audience, and came up on Otello’s spectacular opening storm scene, I had my own lightning flash: Groff was in Craig Lucas’s 2008 off-Broadway play, Prayer for My Enemy. Directed by – ta da! – Bartlett Sher. Between the Lucas title and Yoncheva’s tremendously moving “Ave Maria” in the second half of Otello, it turned out to be a very prayerful day.

Brendan Lemon is the American theater critic for the Financial Times and the editor of lemonwade.com.