Injuries are part of the NFL game, and the San Francisco 49ers are already experiencing their share. Fortunately, the 49ers got rookie wide receiver Ricky Pearsall back in the mix Monday. But unfortunately, the 49ers were dealt a pair of new injury blows at training camp, according to ESPN Senior NFL Insider Adam Schefter.

At the forefront of the woes is the loss of Drake Jackson. A second-round pick in 2022, Jackson has struggled to stay on the field, playing in 23 games but not logging a starting assignment while compiling six sacks. Coming off patellar tendon surgery, Jackson won’t participate in training camp.

Also out is running back Isaac Guerendo, who suffered another hamstring injury in a long line of that type of setback.

49ers’ RB Isaac Guerendo out for multiple weeks

San Francisco 49ers running back Isaac Guerendo (49) runs drills during the 49ers rookie minicamp at Levi’s Stadium in Santa Clara, CA.
Robert Kupbens-USA TODAY Sports

Guerendo suffered a hamstring injury on Day 1 of training camp practice. And a report Monday showed enough damage to keep him out likely past the season opener.

It’s nothing new for Guerendo, who has been an oft-injured player. Guerendo missed 14 games because of hamstring injuries at Wisconsin and also suffered a broken foot. Because of the myriad of injuries, Guerendo made just one collegiate start.

A fourth-round draft pick, Guerendo figured to be in the mix for playing time. But the preseason setback won’t help his cause early in the year. According to sfchronicle.com, Guerendo showed visible frustration after the injury and held his hands on his head on the sideline. He planted awkwardly on the play near the end of a run.

“It looked like he hyperextended a little bit,” Shanahan said. “He was going about half-speed, it looked like. So it was an unusual one.”

It’s not a size issue for Guerendo as he stands 6-foot-1 and weighs in at 225 pounds. He has blistering speed for his size, clocking a 4.33 in the 40 at the NFL Combine.

Guerendo's injury likely clears the way for Jordan Mason to slot into the No. 3 running back slot at the start of the season. Christian McCaffrey, one of the NFL's best players, is the starter. He has a capable backup in Elijah Mitchell.

When will Jackson return to the playing field?

49ers’ head coach Kyle Shanahan told audacy.com there’s not timeline for Jackson’s return.

“I know it won't be any time in camp,” Shanahan said. “We gotta see how rehab goes. I mean any time you do that type of surgery that he had, those are big surgeries. So it's tough to come back from. You never know how they're going to react. It was always a possibility it would take a long time, and it's taking a long time.”

Jackson didn't figure into a starting role on a defensive line that includes Nick Bosa. He's also behind Leonard Floyd. But it's certainly a depth piece Shanahan would love to have as the 49ers try to continue their run of excellence. Over the last five years, the 49ers have played in two Super Bowls and four NFC Championship games.