Mayfield didn't take part in Wednesday's walkthrough due to knee and right biceps injuries, Jenna Laine of ESPN.com reports.

Mayfield was among a number of key skill-position players that were held out of drills to begin Week 5 prep -- the others being RB Bucky Irving (foot/shoulder) and WRs Mike Evans (hamstring) and Sterling Shepard (foot). Meanwhile, WR Chris Godwin (ankle) emerged from his first game action since last season as a full participant Wednesday. Mayfield was limited in all three sessions last week due to a right biceps injury, so the addition of the knee issue indicates he's a bit more banged-up this time around. He'll have two more chances to practice this week to prove his health ahead of Sunday's contest at Seattle.

Jones (knee) will start Thursday at the Rams after Brock Purdy (toe) was ruled out for that contest, Matt Maiocco of NBC Sports Bay Area reports.

Purdy returned from a two-game absence this past Sunday versus the Jaguars but came out of the outing with toe soreness, which didn't allow him to practice this week. Meanwhile, Jones is past the PCL sprain that he dealt with last week following three straight full listings this week. With Purdy sidelined for the third time this season, Jones will retake the reins of the 49ers offense, but the skill positions also will be without WRs Jauan Jennings (ankle/rib) and Ricky Pearsall (knee), meaning RB Christian McCaffrey, WRs Kendrick Bourne, Demarcus Robinson and Skyy Moore and TE Jake Tonges will be the top available options in the passing game.

Purdy (toe) has been ruled out for Thursday's game at the Rams, Matt Maiocco of NBC Sports Bay Area reports.

In his first game action since Week 1 this past Sunday against the Jaguars, Purdy completed 22 of 38 passes for 309 yards, two touchdowns and two interceptions, had two carries for 13 yards and lost a fumble. On Monday, coach Kyle Shanahan revealed that Purdy was dealing with toe soreness, which likely is related to the turf toe variant that sidelined him Weeks 2 and 3. With the 49ers afforded a short week to prepare for Thursday's contest, Purdy didn't have enough time to get healthy, and the 49ers now will turn to Mac Jones under center yet again Week 5.

Dart (hamstring) practiced fully Wednesday, Dan Salomone of the Giants' official site reports.

Dart emerged from his first NFL start this past Sunday versus the Chargers with a hamstring injury after taking five sacks during a 13-for-20 passing performance and two total touchdowns (one passing, one rushing). Prior to Wednesday's session, coach Brian Daboll told Dan Duggan of The Athletic that Dart wouldn't be limited, which has come to pass. Dart thus will resume his standing as the Giants' No. 1 signal-caller as the team prepares for Sunday's game at New Orleans.

Jackson (hamstring) isn't practicing Wednesday, Jamison Hensley of ESPN.com reports.

A hamstring injury forced Jackson out of this past Sunday's loss to Kansas City, which clouds the star QB's status for this weekend's game against the Texans. While coach John Harbaugh has yet to provide an update on Jackson, Brian Wacker of The Baltimore Sun suggested Tuesday that the signal-caller isn't likely to face Houston and could miss two-to-three weeks. If Jackson is indeed sidelined Sunday, Cooper Rush would draw the start in his place.

Coach Brian Daboll said Dart (hamstring) won't have limitations at Wednesday's practice, Dan Duggan of The Athletic reports.

In his first NFL start Sunday against the Chargers, Dart had a modest passing line (13-for-20 for 111 yards, one TD and no picks) while rushing 10 times for 54 yards and a score, but he also took five sacks and was visibly hindered at times. Daboll revealed Monday that Dart was dealing with a hamstring injury but that he was "doing good" and was expected to practice Wednesday, per Ralph Vacchiano of Fox Sports. During Wednesday's team stretch, Dart was spotted with a significant tape job on his upper left leg, according to Duggan, so it remains to be seen if the rookie signal-caller indeed will be listed as a full practice participant to begin Week 5 prep.

Commanders coach Dan Quinn said Daniels (knee) has been medically cleared and will be a full participant in Wednesday's practice, Tashan Reed of The Washington Post reports.

Daniels will return from his two-game absence due to a knee sprain and start Sunday's road matchup against the Chargers. It appeared as though the second-year signal-caller had at least a chance to return Week 4 versus Atlanta, so by this stage there should be minimal, if any, lingering concerns about Daniels' mobility and rushing upside. Meanwhile, Quinn also said things are "trending up" for wideouts Terry McLaurin (quadriceps) and Noah Brown (groin), per Nicki Jhabvala of The Washington Post.

McCarthy (ankle) was not spotted at the portion of Wednesday's practice open to the media, Dane Mizutani of the St. Paul Pioneer Press reports.

Vikings head coach Kevin O'Connell said the "hope is soon" that McCarthy will be "back on an individual level," per Alec Lewis of The Athletic. That said, O'Connell noted that he "probably would not expose [McCarthy] to the look team" in the immediate future, a signal that the second-year quarterback doesn't have a very real chance to be available for Sunday's game against the Browns in London. McCarthy hasn't yet been ruled out for Week 5, but even if active, it's likely he would operate in a backup role behind Carson Wentz. The Vikings will benefit from a bye Week 6, making Sunday, Oct. 19 against the Eagles in Week 7 a more realistic tentative date for McCarthy's return, though it's possible Wentz could retain the starting job if he's able to turn in another strong showing versus Cleveland.

Sanders will remain the Browns' No. 3 quarterback for Sunday's game against the Vikings in London, while Dillon Gabriel moves into the starting role and Joe Flacco serves as his top backup, Adam Schefter of ESPN reports.

Though Flacco will head to the bench after going 1-3 as a starter and averaging just 5.1 yards per attempt and posting a 2:6 TD:INT through the Browns' first four games, he's still on track to remain active Sunday as Gabriel's top understudy. With that in mind, Sanders is poised to be a healthy inactive for the fifth straight game as the team's emergency No. 3 quarterback, though he could eventually usurp Flacco for the No. 2 role or potentially supplant Gabriel as the starter later on in the season.

Flacco is slated to back up Dillon Gabriel in Sunday's game against the Vikings, Mary Kay Cabot of The Cleveland Plain Dealer reports.

With the Browns off to a 1-3 start, a span in which Flacco threw six interceptions, the team will pivot to Gabriel, the No. 94 overall pick in the 2025 NFL Draft. In the wake of the move, Flacco will serve as the team's No. 2 signal-caller, while Shedeur Sanders will continue to be the third-stringer, per Adam Schefter of ESPN.