From a Philadelphia journal interview with Yannick Nézet-Séguin:
I’ve to ask: Do you know that Lang Lang was going to come back again out after he obliterated Saint-Saëns’s Piano Concerto No. 2 in G minor and encore with a solo from Mary Poppins, of all issues?
No, I didn’t. It was a shock to all people. I used to be onstage when he got here again out. And he mentioned one thing to the viewers, however I couldn’t hear what he mentioned. None of us may. After which he begins taking part in. And someone within the woodwinds whispers to me, “I believe he’s taking part in Mary Poppins!” It was a particular second, for positive. So lovely.
You’ve been warned.