From the linked article:
"But all that aside, to have to jump in and play a concerto which you have not prepared, literally at the last minute. Isn't that superhuman?

A concert pianist of Pires' standing is expected to be able to play any of about 50 concertos at the drop of a hat, and as many more at short notice. But they would expect to have a minimum of one rehearsal before a concert, so the conductor and orchestra know what to expect.