Donald has lost one of seven Ryder Cup matches
Injured Luke Donald's hopes of making September's Ryder Cup team suffered a further setback when he withdrew from August's USPGA Championship.
Donald has not played since he picked up a wrist injury during the final round of the US Open in June.
The 30-year-old faces a struggle to qualify automatically for the team and is not guaranteed a wild card entry.
Europe's Ryder Cup captain Nick Faldo has previously said: "To pick a man who is injured would be a major story."
The USPGA takes place at Oakland Hills, Michigan from 7-10 August.
The top five players from both Europe's world points list and the Order of Merit earnings will be selected for the Ryder Cup, which is being held in Louisville, Kentucky.
Donald, who has been a member of the last two victorious Ryder Cup sides, losing only once in seven matches, is currently 11th in the world points standings and 43rd on the Order of Merit.
Five events remain on the calendar before the qualifying deadline on 31 August and, as things stand, Open Championship runner-up Ian Poulter, Colin Montgomerie, Paul Casey and Darren Clarke are also in need of one of two wild cards for the 12-man team.
Clarke's chances of qualification were boosted when the Northern Irishman, 33rd on the points table, received an invitation to the last major of the year.
He was also allowed to compete at this week's World Championship thanks to the wild card Ian Woosnam gave him for the 2006 Ryder Cup.