Poor John. Well, I don’t know if ‘poor’ is the right expression here, but the fact remains that guitarist John Mayer was not able to sing live for almost two years due to ‘Granuloma’, a weird problem in his throat. But those days are over and to everybody’s delight; John was able to perform a bunch of tunes while singing along to his guitar. And from what I read only, even Katy Perry and Taylor Swift were impressed. Well done, John.