The 74-year-old tenor was hospitalised in the Big Apple earlier this month (Oct15) after falling sick while rehearsing to conduct a Metropolitan Opera production of Tosca.

He cancelled a number of planned appearances, including a turn at the Metropolitan Opera's Golden Horseshoe dinner, which is held to thank donors who support the organisation.

However, Domingo stunned the gathering at the St. Regis hotel by making a surprise appearance at the end of the event to sing Nemico della Patria from the opera Andrea Chenier.

"It was electrifying, but we were worried about his stitches," an onlooker tells New York Post gossip column Page Six.

He is expected to return to the Tosca production on 6 November (15).