LOS ANGELES -- The San Francisco 49ers' offense will be even more short-handed than it has been in the season's opening month when it takes on the Los Angeles Rams on Thursday night.
On Wednesday, the Niners ruled out quarterback Brock Purdy (toe) and receivers Jauan Jennings (ribs, ankle), Ricky Pearsall (right knee) and Jordan Watkins (calf).
Those updates are in addition to a list of players already missing that includes tight end George Kittle (hamstring) and wideout Brandon Aiyuk (knee).
On Tuesday, Purdy offered some optimism that he might still be able to play despite the toe soreness that began plaguing him Sunday night after the Niners lost to the Jaguars. But he also cautioned that the short time from Sunday's game to Thursday night would make it difficult.
"With a quick turnaround with a Thursday night game and everything, it's just tougher," Purdy said. "You don't have as many days to get right and heal up and feel better."
With Purdy out, Mac Jones is set to make his third start in the first five games. He led the Niners to wins in Weeks 2 and 3 against the Saints and Cardinals, respectively, but battled a sprained knee coming out of the Arizona win. Jones is back to full strength this week, not appearing on the injury report.
"Just day-by-day getting better," Jones said. "And at the end of the day, you just have to ask yourself if you can protect yourself in the game, and I felt good to go. So obviously every week guys are dealing with stuff, and it's an every-day battle, so you're just working through it."
Jones, though, figures to have his work cut out for him against a Rams defense that he called the best in the NFL on Tuesday. The only healthy receivers on the 49ers active roster going into Thursday are Demarcus Robinson, Kendrick Bourne, Skyy Moore and Marquez Valdes-Scantling. The Niners are also likely to elevate Russell Gage Jr. or Malik Turner from the practice squad, though they'll likely have to do the same for backup quarterback Adrian Martinez, leaving just one spot open for a receiver.
Pearsall and Jennings dealt with injuries leading into the Jacksonville game, with Pearsall battling left knee soreness and Jennings shaking off shoulder and ankle issues. But both suffered further injury against the Jaguars with Pearsall landing hard on his right knee and Jennings taking a big hit to the ribs when catching a 2-point conversion.
Surrounding Jones, the 49ers will likely start Robinson and Bourne at receiver with Luke Farrell and/or Jake Tonges at tight end against a Rams defense that is ninth in the NFL in yards allowed per game (284.5), fifth in defensive expected points added (13.78) and tied for second in sacks (14).
"There's always 11 guys on the screen, and they have a great defensive line," Jones said. "They play a lot of different schemes. They do a lot of stuff but do it well. So, it's going to be a challenge. I've been impressed with them. So, can't wait to go against them."
Elsewhere on the injury report, the 49ers also ruled out defensive end Robert Beal Jr. (ankle) and listed defensive tackle CJ West (thumb) as questionable.
The Niners will get a few extra days off after Thursday's game and then travel to face Tampa Bay in Week 6.