LaMarcus Thompson doesn't remember the lick that gave him a concussion a couple of weeks ago on Tennessee's practice field.
His short-term memory was wiped clean.
But Thompson has been around campus a while and thus has plenty of long-term memory.
Memory of redshirting in 2006.
Memory of playing special teams in every game in 2007 and 2008.
Memory of at long last finally starting fall camp this year with the No. 1 defense at strongside linebacker.
So when he found himself standing around on the sideline again waiting for the doctors to clear him to return to action, it didn't sit well.
"You could definitely say that,'' Thompson admitted Saturday after the Vols' scrimmage at Neyland Stadium. "But that's football.''
Thompson was back in action Saturday. He missed the first scrimmage but got the medical OK to get back to work last Thursday.
He doesn't think he lost any ground, but it wasn't comfortable watching players like true freshman Greg King filling in his vacancy with the No. 1 defense.
"It's definitely a competition,'' Thompson said, "so you definitely have to worry about what's going on.
"But all you can do is go out and play hard as you can and see what the outcome is.''
The junior from Lithonia, Ga., said the coaching staff did a good job of keeping injured players involved thus far during camp.
That group is not insignificant. Linebackers Rico McCoy and Herman Lathers also want to be in competition for starting jobs. So do defensive backs Brent Vinson, Art Evans and Stephaun Raines.
"You stand on the sideline watching practice,'' Thompson said, "but you're getting mental reps and helping out the younger guys.
"The coaches say to get mental reps. It never feels like you miss out on anything. You always have the checks and stuff like that.''
McCoy is the only linebacker with significant SEC experience. He hasn't suited up since the first week of practice. Savion Frazier is working with the first unit in his place.
Nick Reveiz is digging in at middle linebacker. Thompson is trying to hold his ground ahead of either King or another freshman, Jerod Askew.
He was encouraged by Saturday's showing, both by the linebackers and the defense in general.
"Overall we did pretty good,'' he said. "We're reading our keys better. It's night and day from spring practice.''
In his case the best part was being on the field again with the first-string defense.
Mental reps are fine to a point, but nothing can take the place of the physical reps.