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Paul Sakuma, Associated Press
San Francisco 49ers wide receiver Kyle Williams (10) celebrates after scoring on a 56-yard touchdown pass from quarterback Alex Smith during the fourth quarter of an NFL football game against the St. Louis Rams in San Francisco, Sunday, Dec. 4, 2011.

SANTA CLARA, Calif. — Pete Lavorato was at home watching the San Francisco 49ers on Thanksgiving when a play popped up on television that looked all too familiar.

Turned out, his version of the "Fly Sweep" had made it to prime time.

The coach at Sacred Heart Preparatory in the Bay Area had passed along a tip about the play to San Francisco's Jim Harbaugh a couple of years ago. He never imagined seeing the scheme work in the NFL.

The idea is only the latest wrinkle Harbaugh has worked into the 49ers offense.

San Francisco has found creative ways this season to keep opponents guessing about an otherwise vanilla offense, including throwing to a lineman, letting a nose tackle catch a pass and converting a defensive end into a fullback.