PACIFIC PALISADES, Calif. (Reuters) -- Two-time winner Fred Couples withdrew from the Nissan Open on Tuesday because of an unspecified injury, PGA Tour officials said.

The 47-year-old American, who also pulled out before the start of last week's Pebble Beach National Pro-Am, has suffered from back problems for much of his career.

Nissan Open champion in 1990 and 1992, Couples has played in only one event on the 2007 PGA Tour, missing the cut at the Phoenix Open two weeks ago.

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