Fred Couples' often-injured back is keeping him out of this year's Canadian Open. Fred Couples' often-injured back is keeping him out of this year's Canadian Open. (John Lazar/Associated Press)

Fred Couples won't be teeing off at this year's Canadian Open after all.

The popular American has been forced to withdraw from the tournament because of back pain.

Couples tweaked his often-injured back on Monday while playing in Mike Weir's charity tournament at Glen Abbey in Oakville, Ont., the course that will also play host to the Canadian Open.

The tournament runs Thursday through Sunday.

Couples made his first appearance at the Canadian Open in 13 years last summer, finishing in a tie for 20th.

The 49-year-old finished third at two PGA tournaments this year — the Northern Trust Open and Shell Houston Open. He also tied for 11th at the AT&T National three weeks ago.

Couples will captain the American team at the Presidents Cup in October.

With files from The Canadian Press