Brandt Snedeker is taking an "indefinite" break from golf to recover from the rib injury which has kept him out of action since June.
Snedeker, who won the European Tour's Fiji International last October, withdrew from the Open Championship the day before the first round and has not played since.
The 36-year-old wrote on Twitter: "I would first like to thank everyone for their well wishes over the last few weeks, it has meant a lot to me.
"Unfortunately, I have not progressed in my rehab like we would have hoped and therefore will be shutting it down for an indefinite period of time until I get back to 100 per cent healthy.
"My sternum joint has become unstable and does not allow me to hit a golf ball without pain. My medical team and I are looking into every option to get me back to playing as soon as possible.
"It pains me not to be out there on tour competing, but at this time my health needs to be my priority."