Left guard Chris Spencer has been benched after he played poorly in the Bears’ loss to Green Bay. (US Presswire)

Chicago Bears left tackle J'Marcus Webb is not the offensive lineman being shoved to the bench.

Webb, who struggled against Green Bay's Clay Matthews and was shoved by an angry Jay Cutler on Thursday, will apparently keep his job.

But left guard Chris Spencer is going to the bench and is being replaced by former San Francisco 49er Chilo Rachal.

Rachal, who signed in free agency after four seasons in San Francisco, will be playing a new position. He started 38 games at right guard for the 49ers.

"This is the first time playing left guard in my career," Rachal said. "I like it. I am naturally left-handed. I should like this position better than right."

Rachal competed with Spencer, who had been the starting right guard last year and was moved to the left side to start training camp.

In Rachal, the Bears have a slightly bigger player, as at 315 pounds, he's six pounds bigger than Spencer.

"I just approached my work like I do every day," Rachal said. "I came in and got my extra lifts in. I want to take it to another level. This is a good opportunity. I have a small window and I want to maximize this opportunity because you never know when I'll get this chance again."

Follow Bears reporter Gene Chamberlain on Twitter @CBSBears.