Doctor's loss is particularly troubling for the Beavers since they were already short-handed at that position with D.J. Alexander out with a knee injury.
Like the Utes, the rest of the Beavers' linebackers are inexperienced.
Despite the issues, Riley said he was encouraged by his team's handling of the season-opening loss to Eastern Washington and the injuries.
"We've already seen some adversity in these first two games," Riley said. "But I've been impressed with the way the team is handling it and nobody has blinked and we have good leadership from the older guys so it's going full speed ahead."
While Utah coach Kyle Whittingham discounted the Beavers' injuries, noting "everybody is beat up," he acknowledged Saturday's game could be a good time for Utah's defensive line to assert itself against an inexperienced group.
"We think our defensive front matches up with anybody the entire season," he said. "That is how it has been here a lot of years. We're strong up front and this year is no exception."
New returner: Freshman receiver Delshawn McClellon is listed as a kickoff returner along with sophomore Charles Henderson. Running back James Poole, who was listed as a kickoff returner last week, remains the first option for punt returner.
• Some tickets and bleacher seats are available for Saturday's game
• Saturday's game marks the first time the Utes are opening with three straight home games since 1970.