John Mayer has taught himself to play guitar with three fingers after suffering an injury.

The 'Gravity' hitmaker's left index finger has been left unusable for the foreseeable future after he damaged the digit in the door of his truck, but he was determined not to let down fans who want to see him at Dead + Company's residency at the Sphere in Las Vegas this month so he's taken the time to amend his playing and he's now feeling confident.

Sharing a photo of his injured finger, he wrote on Instagram: "Last Thursday I injured my left index finger (truck door), and the first thing that went through my mind was 'I really need that finger in a week.'

"I need all my fingers, but the left index is the team captain of my fretting hand. It will heal just fine, but will be out of commission for a while. In the meantime, I have spent every day practicing guitar using the other three fingers and I think I have it sounding pretty good!"

The 46-year-old musician apologised for his "misadventure" but he is looking forward to the she shows.

He added: "I've always felt like every part of me belongs to these shows, and it's my responsibility to return to the stage each night without screwing up the equipment, and I'm sorry for the misadventure here. The power of the music and the love for these shows will prevail! See ya tonight."

John's close friend Andy Cohen is among those set to see the guitarist in action this weekend.

He commented: "See you this weekend. Gonna be GREAT."

The band performs a different setlist for each night of the residency, so John will have had to work extra hard to get up to speed without the use of his index finger.