SANTA CLARA — The emotional lift of Ricky Pearsall’s return to the field 50 days after he was shot lasted less than a half. Then the San Francisco 49ers had to deal with some more bad news at receiver.

Brandon Aiyuk went down with a right knee injury in Sunday’s 28-18 loss to the Kansas City Chiefs that coach Kyle Shanahan fears is a season-ending ACL tear.

Shanahan said the team was waiting for confirmation from an MRI scheduled for Monday, but the expectation is that Aiyuk will miss the rest of the season in the latest injury blow to a San Francisco team already missing All-Pro running back Christian McCaffrey and other key players.

“I know a lot of teams deal with that,” Shanahan said about the spate of injuries. “Not every team, but we’re dealing with it hard right now. It got worse today. It’s tough.”

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Aiyuk’s Injury Deals Blow to 49ers’ Offense

Aiyuk got hurt late in the first half when was hit on the knee after making a catch in the red zone. He stayed down for a few minutes before being carted to the locker room and was quickly ruled out for the rest of the game.

Aiyuk, who signed a $120 million, four-year extension in late August following a lengthy contract “hold in,” has 25 catches for 374 yards this season. He was a second-team All-Pro last season when he had 1,342 yards receiving.

“Obviously just what BA does for our offense, who he is as a teammate and brother of ours, man, it’s sad,” quarterback Brock Purdy said. “So wish him nothing but the best moving forward. That’s my guy.

San Francisco was already without two of its other top receivers, with Jauan Jennings sidelined by a hip injury that is not expected to be long-term and Deebo Samuel dealing with an illness that limited him to four snaps against Kansas City.

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Pearsall’s Emotional Return to the Field

That put more responsibility on the plate of Pearsall, who was activated from the non-football injury list on Saturday. Pearsall came in for his first play on San Francisco’s opening drive and caught his first career pass late in the second quarter. He finished with three catches for 21 yards.

“He was going to get eased in a little today,” Shanahan said. “That changed a little bit with Deebo going out and it changed a bunch with Aiyuk going out. So he had to do more than we expected today and I was proud of him for handling it. It’s great to have him back.”

Pearsall returned to practice this past Monday for the first time since he was shot in the chest in San Francisco’s Union Square area on Aug. 31. He was hospitalized overnight but avoided damage to any organs and nerves and was back working out at the team facility the following week.

“Obviously my first thoughts through the whole incident was whether I was going to be alive or not,” Pearsall said. “Once I knew I was going to be OK, and I was going to be able to live, the next question was whether I was going to play football again. As soon as I got that answer, that light just grew inside of me and I was super excited to get back out here.”

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Overcoming Adversity and Returning to Action

Pearsall, who was drafted in the first round in April, missed the majority of training camp with injuries to his hamstring and shoulder but was on track to be ready for the opener before he was shot.

It took weeks to get back to full health where he could play in a game.

“The biggest hurdle for me was just recovering from the wound,” he said. “There was obviously a lot of scar tissue built up in the area, and since it was in my chest, under my armpit. … Just working through that, making sure I’m getting that all worked on and getting that scar tissue out. And once I started feeling a better range of motion, pain tolerance-wise, that’s when I was headed in the right direction in practice to return.”

Pearsall proved that on the practice field during the week, but the moment of stepping onto the field for the first time as a professional was the biggest step.

“It meant everything to me,” Pearsall said. “Obviously, all the adversity I just went through this past month. It was really good to go out there with my guys again. I think that’s a refresher for me at the end of the day. When the incident first happened, the first thing I was thinking about was the guys in this locker room, the coaches in the locker room and the entire staff. They did a really good job of rallying around me and making sure I stayed up. It was a huge blessing for me today.”