DETROIT, MI - OCTOBER 16: Alex Smith #11 of the San Francisco 49ers changes the play at the line during the game against the Detroit Lions at Ford Field on October 16, 2011 in Detroit, Michigan. (Photo by Leon Halip/Getty Images)
Alex Smith's fourth-down, 6-yard pass to Delanie Walker gave San Francisco the go-ahead touchdown with 1:51 left, lifting the 49ers to a 25-19 win over the previously unbeaten Detroit Lions.
The play stood after video review.
Detroit had a chance to drive for a tying field goal or a go-ahead TD, but couldn't get a first down against a swarming defense that hit and confused quarterback Matthew Stafford from the start.
David Akers gave San Francisco (5-1) a six-point lead with 1:02 to go with a 37-yard field goal.
The Lions (5-1) had one last shot and came up woefully short. Then San Francisco coach Jim Harbaugh and Detroit coach Jim Schwartz had to be separated on the field after the game. Harbaugh
seemed to say something that fired up Schwartz, and they bumped into each other on the field.