Minshew was injured late in the fourth quarter of Sunday's 29-19 loss to the Denver Broncos.
Pierce will have to decide whether Aidan O'Connell or Desmond Ridder will start Friday's game at Kansas City.
The Raiders, who have lost seven consecutive games to fall to 2-9, could use a spark. Minshew's grip on the starting job was tenuous even before he was injured. He threw 10 interceptions to just nine touchdown passes this season and lost four fumbles.
So it's possible the coaching staff would have eventually turned to O'Connell or Ridder.
O'Connell has been on injured reserve with a broken thumb but was designated to return to practice Monday. That gives the Raiders a three-week window to decide when to activate him. Until that time, O'Connell will not count against the roster.
Having a short week complicates matters. Pierce said there wouldn't be any typical practices as a result, but there would be ways to gauge whether O'Connell is ready to go. Pierce said he would make sure O'Connell is able to grip the ball without pain.
"Putting a player out there who's hurting or injured still, that's not going to benefit the player or our team," Pierce said.
O'Connell started the last half of last season as a rookie, guiding the Raiders to a 5-4 record. He lost the starting job to Minshew in the preseason but got it back six games into the season. That's when he was injured a week later against the Los Angeles Rams.
The Raiders also could turn to Ridder, who replaced Minshew when he got hurt Sunday. Las Vegas signed Ridder off Arizona's practice squad on Oct. 21. He started 13 games for Atlanta last season, passing for 2,836 yards and 12 touchdowns with 12 interceptions.
In relief of Minshew against the Broncos, Ridder completed 5 of 10 passes for 64 yards. He led the Raiders on a last-ditch drive, taking them to Denver's 1-yard line before the game ended.
"He's a competitor," Pierce said. "Obviously, he was dealt a difficult hand. He was thrown in the fire with no reps, but he did move the ball downfield.