After promising rookie running backs Joe Williams and Matt Breida played a prominent role in the preseason opener, their roles were drastically reduced Saturday.
Williams had just one carry. Breida, who was healthy, didn’t play.
Some form of rookie hazing?
Actually, head coach Kyle Shanahan said the kids were shelved because he wanted to get a look at Kapri Bibbs and Tim Hightower. Bibbs didn’t have a carry in the opener, and Hightower didn’t play.
“We’re trying to give them a chance to compete,” Shanahan said. “We see it in practice each day, but in games you want to see what guys do, breaking through those arm tackles, and see how they perform.”
It’s likely that Williams, a fourth-round pick Shanahan lobbied for before the draft, and Bredia, an undrafted rookie, will land on the 53-man roster. And it’s also likely that Bibbs and Hightower are fighting for one roster spot.
On Saturday, the 49ers had possession for just over 21 minutes and Bibbs (4 carries, 6 yards) and Hightower (3 carries, minus-1 yard) did little with their few opportunities. Hightower also lost a fumble on his first attempt.
Whither Ward: Safety Jimmie Ward could be poised to return practice this week after sustaining a hamstring injury on July27 during a conditioning test when the 49ers reported for training camp.
Ward will have workouts supervised by secondary coach Jeff Hafley on Monday and Tuesday, which are off days, with an eye toward returning when the 49ers return to practice Wednesday.
Ward is transitioning from cornerback to free safety, which is a prominent position in the 49ers’ new 4-3 defense.
“We’ll how he responds to that on Monday and Tuesday and, hopefully, we’ll get him ready to go by Wednesday,” Shanahan said.
Up and down, again: For the second straight week, cornerback Rashard Robinson was kicked around just after kickoff.
In the first four minutes, Robinson missed an open-field, third-down tackle along the sideline that would have prevented a first down and was called for pass interference in the end zone.
However, as he did in the preseason opener, Robinson eventually steadied himself: He was stride for stride with wide receiver Demaryius Thomas on an incomplete deep pass and made a strong open-field tackle on running back C.J. Anderson on third down to force a field-goal attempt.
“It a couple bad plays early in the game,” Shanahan said. “We’re still sticking with him.”
Eric Branch is a San Francisco Chronicle staff writer. Email: EBranch@sfchronicle.com Twitter: @Eric_Branch