Kyle Boller will make his first start at quarterback for the St. Louis Rams on Sunday while Marc Bulger rests his injured shoulder.
Bulger didn't throw during Friday's practice and officially is listed as questionable on the Rams' injury report.
"He took some snaps," Spagnuolo said. "He did some handoffs. We've got 48 more hours for the throwing part of it."
Bulger suffered a bruised rotator cuff on his right throwing shoulder during last week's 36-17 loss to the Green Bay Packers. Boller came in and threw two touchdown passes, but the comeback fizzled in the second half. Overall, Boller was 16-of-31 passing for 164 yards with an interception.
Boller is in his first year with the Rams. He had 42 career starts for the Baltimore Ravens, who took him in the first round of the 2003 draft, but Sunday will mark his first start since Dec. 16, 2007. He missed last season with a shoulder injury.
Boller has taken all the first-team snaps in practice this week.
"You want him to play within his personality and you want him to make sure he does the little things right," Rams offensive coordinator Pat Shurmur said. "We've constantly emphasized taking the easy ones and making sure we make the routine plays."
Boller believes he's ready.
"You've got to be confident in your abilities and, especially in this position, believe in yourself," he said. "I think it's a huge opportunity. We're looking to win a football game here. That's all I'm thinking about -- doing everything I can to lead this team to victory.
"I'm not worried about the future and how it goes. I'm worried about this game and this moment."
Boller is much more agile than Bulger and said he won't alter his style of play, even though the Rams have just two healthy quarterbacks. Boller said he'll even throw a block if necessary -- just as he did last week to help running back Steven Jackson gain an extra couple of yards.
"I love doing that kind of stuff," Boller said.
Null, a sixth-round draft pick out of West Texas A&M, knows he's just an injury away from seeing his first regular-season action.
"I feel fine," he said. "I'm still preparing and I'm trying to be ready if they need to call my name."
David Vobora is out for four games because of a violation of the NFL drug policy, and Larry Grant and Paris Lenon are battling for the strongside linebacker job.
The Associated Press contributed to this report.