WATCH: Roger Federer moved to tears during an Andrea Bocelli concert in Zurich

Is someone cutting onions in Zurich? We’re asking for Roger Federer, who was reduced to tears on Monday evening after witnessing a powerful performance by Italian tenor Andrea Bocelli.

Federer has been living his retirement to the fullest since waving goodbye to professional tennis in an emotional ceremony at last year’s Laver Cup in London. He has stayed close to the sport with farewell appearances at Wimbledon, Halle, the Vancouver edition of Laver Cup, and most recently he was celebrated at the Rolex Shanghai Masters.

This week, the 20-time Grand Slam champion was back home in Switzerland where he took in a concert by Bocelli—the blind opera virtuoso who is considered to be the most successful classical artist of all time—at the Hallenstadion in Zurich.

Federer was caught by surprise at the end of the night, when the legendary singer invited him onto the stage during his closing number, 'Nessun Dorma':

The performance was so moving that Federer quickly became emotional and could be seen wiping away tears throughout. The pair shared a hug and, after Bocelli took his bows, Federer accompanied the Italian offstage.

“The Maestro of singing and the Maestro of tennis. Goosebumps…” one fan wrote on X, the platform formerly known as Twitter.

“Legend recognizes Legend,” another fan added.

Check out another angle to see more of Federer’s onstage moment at Bocelli’s concert: