Given that he was about to start playing the same piano piece 840 times, for no less than 16 unbroken hours, you could have forgiven Igor Levit for appearing panicked as he walked on stage at London’s Queen Elizabeth Hall on Thursday morning.

But the German pianist, beginning a marathon concert in which he would play Erik Satie’s Vexations to hundreds of people for hours on end, simply arranged his sheet music, gave a little laugh – maybe at the absurdity of what he had signed up for – and began to play.

About 150 people had paid to stay for the duration of the marathon performance, which is a collaboration between Levit and the Serbian conceptual artist Marina Abramović.

A South Bank spokesperson said 92% of durational tickets (those in it for the long haul) had been sold and tickets were still available for the hourly evening slots.

It is thought to be the first time the piece will be played in its entirety by the same person live in the UK. Some people opted to pop in for hour-long sessions throughout the day and into the evening, with the last slot beginning at 11pm and lasting until the bitter end.

Jacob Povey, a 29-year-old nurse, was in it for the long haul. “It’s such a unique, once-in-a-lifetime opportunity,” he said as he waited for doors to open. “I’ve managed five hours before at Christian Marclay’s film installation The Clock, so I know I’ve got something like that in me. I’ll be in and out, but hopefully I’m here at the end … whenever it does actually end.”

Written in 1893 for keyboard, Vexations is between one and two minutes long when played once. But a note from Satie on the manuscript – “In order to play this motif 840 times in a row, it would be advisable to prepare oneself beforehand, in the deepest silence, through serious immobilities” – has inspired several artists over the years to attempt just that.

A marathon performance of the piece in 1963, organised by John Cage and played in shifts by various pianists including Christian Wolff, lasted 19 hours and was called “musical history” by the New York Times.

Levit, whose first performance of the piece was streamed from his Berlin apartment during the Covid-19 lockdown, has done it before in 15 and a half hours.

For many visiting, it was less about the music and more about the performance, which featured pieces of the modular stage being taken apart and turned into sculptural chairs.

“One of the things that struck me was how unmemorable that piece of music was,” said Dave Hallberry, 69, who had come along to the performance with his wife, Noreen, and 18-year-old daughter, Sorcha.

“Even now I don’t think I could sing it to you, and I’ve just been listening to it for an hour. There’s something about the combination of notes that makes you want to keep listening to it.”

Abramović worked with the lighting designer Urs Schönebaum and set designer David Amar to create a mirror-like effect above the piano. Clare Maleeny, a 24-year-old film editor in the audience, said: “I kept switching my view between the mirror and the stage. It was trance-like.”

Ruth Davis, 69, an Alexander teacher, was more familiar with the piece than most. “They said it was the first time that it’s been played live in the UK,” she said. “Which is not true: I played this piece in front of an audience in 1983 for my second-year performance at Leicester Polytechnic and it lasted 11 hours and 43 minutes. I starved myself for two days before. It’s really quite a difficult piece to play!”

Luckily, Levit had two onstage helpers nearby to provide him with sustenance and mop his brow. And as for the key question on everyone’s mind – how he went to the toilet – a screen was on standby to go up around the piano.

Many, though, worried about his comfort and wondered whether he would go the distance. “The chair wasn’t great,” Hallberry said. “I thought he’d have some sort of comfy office chair or something.”

Speaking to the Guardian earlier this year, Abramović said the chair could turn into a bed, “so that he can lie next to the piano for 10 or 15 minutes if he needs to”.

For the audience as much as for Levit, it will be a test of endurance.

“I will have to leave for toilet breaks and eating and so on,” said Nick Manrique, a 26-year-old PhD student. “But I’m stubborn – I’m quite determined to see it through.”

• Tickets for Igor Levit’s performance of Vexations – including one-hour time slots – were still available on Thursday from the Southbank Centre box office.