Canan Moodie will miss the Bulls' URC clash against the Scarlets after failing to pass fitness tests on his hamstring, sustained during last weekend's 47-7 win over the Dragons in Newport.
Moodie lasted just 40 minutes before being withdrawn at half-time, and despite treatment beginning on Tuesday, concerns remained during Thursday's training run.
"We obviously treated him and started to test him from Tuesday, but yesterday with the run, there were still signs that it's not 100 percent," head coach Johan Ackermann said. "At this stage of the season, it's too big a risk to push him and potentially worsen the injury."
With a bye week to follow, Ackermann is hopeful the injury is not serious. "We're hopeful it's not too serious and that he'll be ready when we return," he added.
Sergeal Petersen also remains unavailable with concussion. On the positive side, Kurt-Lee Arendse and Cheswill Jooste are both back in contention for the Scarlets fixture.