Isaac Guerendo is only seven games into his NFL career and has registered double-digit carries in just two of them.

Still, San Francisco 49ers head coach Kyle Shanahan has seen enough from the fourth-round rookie to be confident he is ready for the opportunity that now awaits him.

Guerendo will be the 49ers' lead back after Christian McCaffrey was placed on injured reserve, with Jordan Mason set to follow him because of a high ankle sprain.

The former Louisville and Wisconsin back, who wowed at the Scouting Combine with an outstanding workout that included a 40-yard dash of 4.3 seconds, has sporadically displayed his big-play ability in his first season. Guerendo had a 76-yard run against the Seattle Seahawks in Week 6 and went for 85 yards and a touchdown in a win over the Dallas Cowboys two weeks later.

Guerendo scored the 49ers' only touchdown in their blowout loss to the Buffalo Bills last Sunday and, speaking ahead of their Week 14 meeting with the Chicago Bears, Shanahan expressed faith in a player for whom San Francisco traded up in this year's draft.

"I think he's ready to go," head coach Kyle Shanahan said on Wednesday. "He got off to a late start with injuries in preseason. I thought he finished in those games, especially that [93-yard] kick return he had versus the Raiders, I think. He did some decent things when he started out. Didn't get a lot of carries, had some ups and downs, but got better through everything.

"And then, when he got the bulk of the carries—I want to say some more versus Seattle—he only got better, and he's gotten better throughout the year. So I think he's ready for this."

Shanahan had specific praise for how Guerendo has developed in terms of his decisiveness hitting the running lanes, adding: "I think it takes guys some time. You start to get a feel for it, if you've got the right stuff, the more you get reps, the more you can adjust to it, how hard you got to hit stuff, how quick those holes close, how, when there is a hole, how you have to hit at full speed and can't hesitate at all or it closes like that.

"So we've seen that stuff get better in practice, and we've seen it carry over to games."

The 49ers on Tuesday claimed Israel Abanikanda off waivers from the New York Jets to help fill out their backfield, and they made more moves on Wednesday, promoting Patrick Taylor Jr. from the practice squad, to which they signed Ke'Shawn Vaughn. 

Their running back room looks substantially different than it did when the 49ers initially set about preparing for Week 1 still believing McCaffrey could play. But, with Guerendo leading the way, there's still optimism it can be a productive group over these final five weeks of the season.

49ers rookie’s performance in first NFL start offers further evidence of his status as hidden gem

He’s going to have a big role in the coming years.