This week, Mumbai will play host to Maria João Pires, an internationally-acclaimed pianist from Portugal who has been touring the world since the 1970s.

Pires is particularly known for her expressive renditions of music by Mozart, and when she plays with the Symphony Orchestra of India at Mumbai’s National Centre for the Performing Arts on September 21 and September 23, one of the pieces she will perform is Mozart’s piano concerto in E-flat major.

But there is another Mozart composition that made 70-year-old Pires an online sensation last year, after what came to be known as a miraculous concert.

In October 2013, Pires went to Amsterdam prepared to perform Mozart’s piano concerto in C-major at the city’s famous Royal Concertgebouw. But when the orchestra started to play the introduction, she was in for a shock: they were playing a different piece – Mozart’s concerto in D-minor. It soon became apparent that Pires had rehearsed for the wrong piece.

It was every concert performer’s nightmare. As is evident from the widely-shared video above, Pires was in a state of panic. She can be seen telling conductor Riccardo Chailly that she didn’t have the sheet music for the piece that was being performed. Chailly, while continuing to lead the orchestra through the opening bars, calmly mouthed words of encouragement: “You know it [the piece] so well, you played it last season.”

A few seconds later, when it was time for Pires to begin her solo notes, she made sure the show went on. The anxiety was still evident on her face, but it also found its way into her music. She played the piece flawlessly, beautifully and with a poignancy that perhaps would not have been had she come prepared for the Mozart D-minor.