"He pulled away from a stop street when an old lady raced over the red light, knocking the rear side of his motorbike right out from under him," Van Der Merwe told Die Son.
"Luckily, nothing was broken. He had to get a few stitches and picked up a few bruises, but he won't be out for long."
Van der Merwe admits he is looking forward to having Russell in the side once he returns to training.
"We all know Brent is deadly with ball in hand. His counter-attacks can rip any side's defence to shreds," added the coach.
The Stormers have warm-up games against the Bulls on January 13 and Boland a week later, before their Super 14 season gets underway with a trip to the Cheetahs on February 3.