SAN FRANCISCO (AP) -The San Francisco 49ers have taken a big blow to their already struggling offensive line, losing right tackle Tony Pashos for the season with a broken left shoulder blade.

The 49ers placed Pashos on injured reserve Tuesday after he had an MRI Monday. He was hurt during Sunday's 24-21 loss at Houston, his first start at right tackle in place of Adam Snyder.

Coach Mike Singletary had hoped making Pashos the regular right tackle would help improve things on the line. Pashos had been sharing right tackle duties with Snyder, who moved into a shared role at right guard with Chilo Rachal.

Singletary has called the line his biggest concern. San Francisco plays at Indianapolis on Sunday with newly promoted quarterback Alex Smith set to start.