Running back Matt Breida’s successful yet injury-plagued season came to an end on Sunday.

Breida aggravated an ankle injury on Sunday in the first half of the 49ers’ 14-9 loss to the Chicago Bears. Coach Kyle Shanahan said Breida will not be available for the team’s Week 17 game against the Los Angeles Rams.

Rookie wide receiver Dante Pettis will also sit out the final game of the season with a knee injury. Pettis sustained a partially torn medial-collateral ligament in the first half of Sunday’s game. The injury will not require surgery. Both Pettis and Breida are expected to be available for the start of the team's offseason program.

Tight end Garrett Celek was diagnosed with a concussion. He is in the NFL’s concussion protocol. Wide receiver Marquise Goodwin (bruised calf) and cornerback K’Waun Williams (knee) will be re-evaluated on Wednesday, when the 49ers return after two days off.

Breida was one of the bright spots for the 49ers this season, as he was forced to carry the load after being elevated early in the season to a role as the team’s every-down back.

Veteran Alfred Morris was the starter in the 49ers’ season opener, just one week after presumptive starter Jerick McKinnon was lost with a torn ACL. But it did not take long for Breida to win the permanent starting role.

“I think Matt’s had a very impressive season,” 49ers coach Kyle Shanahan said Monday on a conference call with Bay Area reporters.

“He started out great, filling in, losing McKinnon at the beginning of the year. And I think Matt stepped in right away and played like a No. 1 back.”

Breida started 13 games and rushed for 814 yards and three touchdowns on 153 attempts. He averaged 5.3 yards per rushing attempt while battling knee, shoulder and ankle issues most of the season.

Breida sustained an ankle injury in Week 5 against Arizona that lingered the remainder of the season.

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“He got hurt early on and he battled every week to get in there and play for us,” Shanahan said. “He ended up hurting it every week, also, so it’s lingered all year. It's just a credit to him to still be effective when he’s been out there, and to be able to help us throughout the year has been unbelievable.”

Breida made the 49ers’ 53-man roster as an undrafted rookie in 2017 from Georgia Southern. He beat out Joe Williams, a fourth-round draft pick, and rushed for 465 yards as Carlos Hyde’s backup.

“He showed what he showed last year at the end of the year and he got only better,” Shanahan said. “That’s what was neat about him. He was still able to play through injuries and stuff.”

If McKinnon returns to full strength for next season, the 49ers should be in good shape with Breida and, potentially, Raheem Mostert in backup roles. Mostert is scheduled to be a restricted free agent. Rookie Jeff Wilson has also placed himself in position to compete for a job.

Mostert entered the season as a special-teams ace, but played well as a running back before sustaining a season-ending fractured forearm in Week 9 against the Raiders. Mostert carried 34 times for 261 yards – a 7.7-yard average.