SEATTLE — The San Francisco 49ers blew a career day from quarterback Alex Smith, more opportunities to win than they could have wished for — and a chance to keep pressure on Arizona in the NFC West.

Olindo Mare kicked a 30-yard field goal as time expired to send Seattle (5-7) to a 20-17 victory yesterday over San Francisco (5-7).

Smith threw for a career-high 310 yards in the 49ers' new spread offense. The No. 1 overall pick in 2005 completed 27 of 45 throws and had two touchdown passes.

San Francisco will regret its blown chances: two incompletions from the Seahawks 1 in the opening quarter; a fumble on a punt reverse; another fumble by Frank Gore at the Seattle 22; and an ill-timed three-and-out in the final minute that left Seattle time and field position for the winning drive.

"It's a load off when they take care of one of our problems for us. It was ... beautiful," Seattle rookie outside linebacker Aaron Curry said.

SAN FRANCISCO 7 7 0 3—17

SEATTLE 7 7 0 6—20

First Quarter

SF—V.Davis 33 pass from A.Smith (Nedney kick), 6:16.

Sea—Branch 7 pass from Hasselbeck (Mare kick), 3:48.

Second Quarter

Sea—Forsett 8 pass from Hasselbeck (Mare kick), 10:06.

SF—Morgan 22 pass from A.Smith (Nedney kick), 7:40.

Fourth Quarter

Sea—FG Mare 25, 5:30.

SF—FG Nedney 34, 2:57.

Sea—FG Mare 30, :00.

A—67,761.

SF Sea

First downs 14 17

Total Net Yards 356 292

Rushes-yards 12-53 29-107

Passing 303 185

Punt Returns 5-(-3) 7-61

Kickoff Returns 3-73 4-88

Interceptions Ret. 0-0 0-0

Comp-Att-Int 27-45-0 26-35-0

Sacked-Yards Lost 1-7 5-20

Punts 9-49.6 10-44.7

Fumbles-Lost 2-2 2-1

Penalties-Yards 8-57 4-48

Time of Possession 28:49 31:11

RUSHING—San Francisco, Gore 9-25, Morgan 1-20, Walker 1-7, A.Smith 1-1. Seattle, J.Jones 20-67, Hasselbeck 4-31, Forsett 5-9.

PASSING—San Francisco, A.Smith 27-45-0-310. Seattle, Hasselbeck 25-34-0-198, S.Wallace 1-1-0-7.

RECEIVING—San Francisco, V.Davis 6-111, Crabtree 6-60, Morgan 6-56, Gore 5-37, Walker 3-28, Jones 1-18. Seattle, Burleson 5-54, Houshmandzadeh 5-37, J.Jones 5-(minus 3), Forsett 3-25, Griffith 3-25, Butler 1-32, Obomanu 1-12, Carlson 1-9, Branch 1-7, Rankin 1-7.

MISSED FIELD GOALS—None.