Anthony Kulkamp Dias, a 33-year-old man in Brazil, recently underwent brain surgery to remove a tumour, and managed to perform this pretty impressive rendition of The Beatles’ “Yesterday” during the procedure. The footage, above, was filmed by the staff at Nossa Senhora da Conceição hospital in the state of Santa Catarina, where the procedure was conducted. This was the first time a patient had ever played guitar during brain surgery in Brazil.

While it seems a little unnecessary, Dias's performance was actually a crucial part of the challenging, nine-hour surgery. Being able to hear Dias sing and play the guitar helped doctors conduct ‘cerebral monitoring’ and make sure that the work they were doing wasn't damaging any parts of the sensory, motor or speech areas of the brain.

The Beatles fan and former professional guitarist followed up his performance of "Yesterday" with a song he wrote for his son, as well as some Brazilian folk songs. “The doctors asked me to repeat one of the country songs so I even had an encore,” Dias told Brazilian news website G1, as The Telegraph reports.

This isn't the first time music has made its way into the surgical suite - last year, a violinist performed through a different type of brain surgery to help his doctors out.

Dias, who now works in a bank, first noticed he may have a problem when he started stammering words and struggling to pronounce them. Removing tumours that are embedded deep in the brain is always challenging, as there's the risk of damaging other structures. But although Dias was awake during the entire tumour removal process, he was fully anaesthetised and didn't feel any pain.

The surgery was reportedly a success, with 90 percent of the tumour being removed. Dias has since been discharged.