A reminder of the San Francisco 49ers' uncertainty at wide receiver landed in our inbox when the team released its physically unable to perform list for the start of training camp.
Wide receivers Mario Manningham and Kyle Williams were joined by linebacker Darius Fleming and running back Kendall Hunter on the list. Running back Marcus Lattimore, defensive tackles Tank Carradine and Quinton Dial and offensive tackle Luke Marquardt were placed on the non-football injury list.
Manningham's trip to the PUP list is not a surprise. He's coming off multiple knee surgeries and is a legitimate candidate to start the season on the PUP list, which would ensure he misses game action.
There had been more optimism for Williams, who like Manningham, sat out organized team activities, but the 49ers were hopeful he would be ready for training camp. Williams is coming back from surgery to repair a torn anterior cruciate ligament.
Manningham and Williams join Michael Crabtree (Achilles tendon surgery) as question marks as a new season approaches. The uncertainty likely played a role in tight end Vernon Davis working with wide receivers in minicamp.
Lattimore's designation also was expected. The running back -- on the comeback trail after a devastating knee injury ended his college career -- told NFL.com's Jeff Darlington last month he "probably won't do training camp." He hopes to join the 49ers in practice by midseason. Don't be surprised if the running back is effectively redshirted as a rookie.
Players on the PUP list in training camp can begin practicing once they pass a physical exam. Players on both lists count against a team's 90-man roster.
Veterans will report to 49ers camp Wednesday. Rookies arrived Friday.
Follow Dan Hanzus on Twitter @DanHanzus.