San Francisco wide receiver Mario Manningham went down with a left leg injury early in the third quarter when he was tackled low by Leroy Hill and fumbled.
The loss of Smith affected the entire defense. Aldon Smith was left stuck on 19 1-2 sacks after being locked up by Seattle offensive tackle Russell Okung.
‘‘We can’t make excuses,’’ 49ers’ safety Donte Whitner said. ‘‘We understand: We lost the football game; we lost an ugly football game.’’
NOTES: Lynch finished with 111 yards on 26 carries, his third straight game over 100 yards vs. the 49ers. ... Seattle was 11 of 13 on third-down conversions, a season-high. ... The 49ers were held to 82 yards rushing, just the third time this season he was held under 100 yards.
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