SANTA CLARA, Calif. -- The two running backs behind Carlos Hyde on the San Francisco 49ers' depth chart have combined for a whopping one carry and 6 yards in their NFL careers.

That inexperience didn't stop Niners general manager John Lynch and coach Kyle Shanahan from rolling with undrafted rookie Matt Breida and young journeyman Raheem Mostert as Hyde's primary backups. It also didn't stop them from releasing an established veteran like Tim Hightower over the weekend.

So as San Francisco begins preparations for the season-opener against the Carolina Panthers on Sunday, the running back depth chart looks something like this: Hyde, Breida, Mostert. And though Lynch acknowledged Saturday that the Niners will keep their eyes open for depth, he's content with the group the team has in place.

"I think options are available," Lynch said. "Right now, we have three and that’s likely what we’ll dress. We have three and our offensive weapon in Kyle Juszczyk. Hightower made a big impression on us. He’s someone that Kyle is very familiar with and so we’ll continue to look at him and any other option that we feel can improve our chances."

As it stands, the thing the Niners believe best helps their chances is leaning on the back who is, by far, their most accomplished. That would be Hyde, who rushed for a career-high 988 yards and six touchdowns while averaging 4.55 yards per carry in 2016. Where some once questioned Hyde's fit with this year's team, he has clearly established himself at the top of the pecking order after arriving to camp in the best shape of his career and impressing coaches with his improvement as a pass-catcher.

Even with the talented Breida making a strong impression in camp, Hyde will be the first option even if he's not the only one.

"I would tell you that all three of those guys, if you’ve watched Kyle over the years and Mike Shanahan, [running backs coach] Bobby Turner, these guys, if you are on the roster as a running back, you’re likely going to play," Lynch said. "Raheem Mostert gives us a tremendous asset as a special teams player as well but absolutely Carlos is going to be featured in this deal but Matt Breida is very much a part of our plans. He’s a guy who from Day 1 showed up here and you didn’t have to be like a football savant to see that guy can move and he can move fast and he’s a smart football player and he has the intangibles."

Lynch went on to talk about how Breida suffered what looked like a hyperextended knee early in camp and when trainers surrounded him, he all but shoved them away because he did not want to miss a snap.

"Little things like that tell you that he had the makeup that we wanted and we continued to push and give him opportunity and he continued to prove what we thought to be the right assumption exactly that," Lynch said. "So now, just like I said earlier with all these rookies, they’ve got to go show that they can do it on the big stage but we feel very positive about Matt Breida and what he brings to the table."

Breida's emergence was indeed easy to see early on but there was another rookie who wasn't quite able to fulfill his promise in his first effort. Joe Williams was the back that Shanahan and Turner identified in the draft as perhaps the next in a long line of lesser-known runners capable of posting big numbers in their outside zone rushing scheme.

But Williams took some time to get in shape and then struggled with ball security in camp and preseason games. He aggravated a previous ankle injury in the preseason finale against the Los Angeles Chargers and landed on injured reserve, ending his first season before it began.

"Once they did scan it, we made the decision along with our medical staff that this was the best course of action for Joe," Lynch said. "That’s a tough loss because he’s a guy that we felt could really contribute in a big way for us. I think everybody saw the unique capabilities Joe has. He’s got game breaking speed, tremendous vision. He’s going to be a big part of our future in my mind and so disappointing we had to put him on injured reserve but the right thing to do in our minds."