On Friday, quarterback Mark Sanchez was carted off the field with a dislocated kneecap. The initial reaction from the USC coaching staff was to instruct junior wide receiver Garrett Green to begin warming up his arm.
Besides Sanchez, the only other scholarship quarterbacks on the roster are Mitch Mustain and Aaron Corp.
To help with depth, Green was asked to move back to quarterback, a position he has played off and on throughout his career at Troy.
"(Friday), in the middle of practice, we asked him to change shirts, take off your gloves, get rid of all your junk like wristbands, take off all that stuff off and get back to quarterback," Pete Carroll said.
Green is no stranger to sudden position changes.
Back in 2006, soon after he chose to attend USC over UCLA and Harvard, Green arrived at camp buried deep on the quarterback depth chart.
Early in the season, Green was moved over to safety and saw significant playing time on special teams. He played in 10 games his freshman year, and then moved back to QB late in the season.
"We told him when he came here that this could happen," Carroll said.
His sophomore year, Green stayed on offense, but as pass catcher instead of a pass thrower. He also continued his role covering kicks on special teams.
This spring, Green stuck with receiver and added extra special teams duties to his resume like holding on placekicks.
Now, just three days into his junior year, Green is moving positions yet again.
"It's cool. It is fun getting back into it though I haven't thought like a quarterback in a while," Green said. "It's a blast and what I have been doing for years. Obviously rusty doesn't being to describe (my play), but it is a blast and I am having a lot of fun."
Green saw his first real quarterback work during Saturday's practice, taking third string reps behind Mustain and Corp.
"I felt better than I thought, but it is kind of a double-edged sword," Green said. "I think a lot of the reason I was doing better was because I didn't have the entire mental part of it to think about. Whether that is a good thing or bad thing yet, I don't know.
"I completed a few balls and I am having fun running around with these guys and filling in where I can."
Learning new positions all of the time can be challenging, but Green knows he can use the knowledge he gained playing safety and receiver to his advantage as a signal caller.
"I think it does help," Green said. "Just understanding the entire route running stuff and what is going on in their head, it definitely helps."
Besides the added depth, Green also brings some experience and athleticism to the position for Troy.
"He has a longer background in knowing the offense and knowing the terminology and all of that stuff," Carroll said. "He is very comfortable calling the (plays in) the huddle and he is a good athlete. We are lucky to have him jump in there."
Green has also done something that none of the current USC quarterbacks, including Sanchez, have done.
Back in January, Green lined up as a receiver early in the game against Illinois. John David Booty flicked a backwards lateral to Green who then uncorked a pass across the field to tailback Desmond Reed.
The result, a 34-yard touchdown pass for Green in the Rose Bowl.
"I don't know if that will get me up in the starting position," Green joked.
For the foreseeable future, Green is prepared to come to practice sporting the bright yellow jerseys that the quarterbacks always wear.
Worn for their protection, other players know not to hit anyone in the yellow jersey.
Early on Saturday tight end Anthony McCoy came up to Green and pushed him around.
"I'm in yellow today," Green said. "No hands."
You can reach Ryan Abraham at firstname.lastname@example.org.