Fred Couples, unable to play the Open last month because of a recurrence of back trouble, has now pulled out of this week's USPGA Championship as well.

The 44-year-old former world number one still had a chance of qualifying for the American Ryder Cup team but needed to win at Whistling Straits on Sunday.

He became the ninth player to withdraw from the final Major of the year following Jeff Maggert (wife expecting twins), Tom Watson (neck), Thomas Bjorn (neck), Toshi Izawa (sinus infection), Nick Price (family obligations), Retief Goosen (hip), Steve Elkington (groin) and Larry Nelson (wrist).

American Ben Crane comes in for Couples and is actually the 10th reserve called up because Tom Byrum took the spot available for Sunday's winner of the International tournament. Australian Rod Pampling, who pipped Alex Cejka, was already exempt.