Australian Jason Day's injury problems show no sign of easing after he decided to pull out of next week's Players Championship.
The world No 6 is still struggling with the thumb injury that has kept him on the sidelines for most of the past two months.
Day has played only once - at the Masters, where he tied for 20th place - since winning the WGC-Accenture Match Play Championship in February.
The 26-year-old had his left thumb put in a cast after last month's Masters in an effort to speed up the ligament healing process.
However, he will not be fit in time to play in The Players Championship at the TPC Sawgrass in Ponte Vedra, Florida - the PGA Tour's flagship event.
"Day suffered a slight setback while playing the Masters and the thumb has been a bit slow to heal," Day's agent said in a statement.
"He is still a few weeks away from resuming normal golf activities."