Arizona State linebacker Brandon Magee didn't practice again on Thursday and will not play in Saturday's game against Nevada-Las Vegas.
The true freshman, who injured a pectoral muscle while lifting weights on Tuesday, has six tackles this season. The linebacker corps is thin because starting middle linebacker Gerald Munns (finger) won't play either and reserve Chad Lindsey left the team this week.
Mike Nixon is expected to start at middle linebacker, flanked by Travis Goethel and Ryan McFoy. Shelley Lyons, Jeff Bereuter and Oliver Aaron will be the backups.
Running back Keegan Herring (hamstring) and tight end Andrew Pettes (groin) will be game-time decisions.
"I won't know anything on those guys until Saturday," coach Dennis Erickson said.
Herring missed the season opener against Northern Arizona, then had 12 rushes for 59 yards and a touchdown last week against Stanford before tweaking the injury.
Pettes was the first-team tight end heading into the season.
"(His absence) affects (getting tight ends involved) a lot, but Dan Knapp had a good game last week and so did Jovon (Williams) so it gives those guys a chance to get better," quarterback Rudy Carpenter said.
Erickson believes Nevada is a fertile recruiting ground.
One of the highest rated players in this year's freshman class, defensive lineman Lawrence Guy, is from Las Vegas, and Erickson signed current St. Louis Rams running back Steven Jackson from Nevada when Erickson was the coach at Oregon State.
"It's growing like Phoenix is," Erickson said.
"There are a lot more high schools and a lot more players, so we'll continue recruiting there hard."