Cape Town - Stormers fullback Joe Pietersen is a doubtful starter for Saturday's Super Rugby derby against the Bulls at Newlands.
Allister Coetzee, the Stormers head coach, on Monday said Pietersen suffered a "lammie" (haematoma) against the Kings on Saturday when he took a knock to the leg.
"Joe has been withdrawn from training sessions and we'll assess his condition on Wednesday," said Coetzee.
"It's the kind of injury that needs complete rest, but I'm optimistic that he'll be okay to play against the Bulls."
If Pietersen did not pass a fitness test, wing Gio Aplon is likely to move to the fullback berth.
"Both (substitute) Gerhard (Van den Heever) and Aplon did well against the Kings over the weekend," said Coetzee.
"If Joe is ruled out, Gio will wear the number 15 jersey, and Gerhard will play at wing. A team change such as this won't prove disruptive at all."
New Springbok Sevens player Cheslin Kolbe is also in the Stormers squad, but Coetzee ruled out a place for the fullback in Saturday's match-day squad.
"We've got Cheslin, but this is not the time to blood him at Super Rugby level," said Coetzee.
"There is plenty of time to give him a run in the Currie Cup and we are looking forward to that.
"At this stage he's under-prepared for Super Rugby, and he is not familiar with our (playing) systems yet.
"He is a star talent and must be managed properly."
The other injury concern is in the backline.
Centre Damian de Allende sprained an ankle and will be rested until Wednesday.
However, regardless of his condition, De Allende will be making way for captain Jean de Villiers, who returns after an injury lay-off.
"Jean is after all our captain and he's ready to play," said Coetzee.
One player expected to return from injury this week is hooker Tiaan Liebenberg.
However, he is not in the running for selection.
"Tiaan is not ready yet and I'd say he needs another week of rehab before we can consider him," said Coetzee.