Kansas City Chiefs training camp gets its unofficial start this week, with quarterbacks and rookies reporting to St. Joseph, Mo., on Friday.With that in mind, here are five Chiefs who have something to prove over the next few weeks of practices.Patrick MahomesThe first one is obvious, and it will be the story of training camp.Quarterback Patrick Mahomes has made remarkable strides since having surgery to repair a torn left ACL and LCL in December — he even participated during most of the team’s May and June practices. But there is still a lot he’ll have to prove physically before we know whether he’ll be available for Week 1.Three storylines I'll be watching in Chiefs training campJesse NewellMahomes did non-contact work during summer drills (while wearing a heavy knee brace) but was held out of 11-on-11s as a precaution. He told reporters in late May that running and cutting would be the next milestones as he worked his way back.One would expect the competitive Mahomes will want to get back to full work in training camp practices soon so he can test himself. So, how will he respond to having added stress on the knee? And what will it be like to work around some discomfort that’s likely to make him less mobile than in years past?Mahomes will have a lot to prove to the medical staff — and himself — before he’s cleared to start the season opener.Rashee RiceReceiver Rashee Rice was my pick for the Chiefs player with the most on the line this season, and he enters 2026 at a career crossroads.Entering the final year of his rookie contract, he has been unreliable over his three seasons, battling injuries while also making poor off-field choices that have too often dragged the Chiefs into negative headlines. The latest was when he violated his Dallas County probation and was forced to immediately serve a previously sentenced 30-day jail term this spring, which kept him away from the team during OTAs and mandatory minicamp.Rice had cleanup surgery on his right knee in May that wasn’t expected to be serious, but it’s another thing to monitor in training camp as he looks to regain the confidence of coaches and teammates.A wide range of outcomes is possible. If Rice is healthy and available, he could be in line for huge production in an offense that values and accentuates his run-after-catch ability.With another injury or away-from-football slip-up, though? It’s tough to gauge exactly what Rice’s free-agency market might be if he goes through another lost season.Training camp figures to be critical for Rice as he needs to show he’s healthy and quickly rebuild chemistry with Mahomes after missing those May and June reps.Jaylon MooreOne of the most significant things we learned during minicamp in June was this team is entering the season with an open competition at right tackle.That’s probably a surprise if you weren’t following along until now. Veteran Jaylon Moore — the Chiefs signed him to a two-year free-agent deal in 2025 — was the presumed starter heading into summer practice, but coach Andy Reid acknowledged in June that the team was sorting through options with Esa Pole and Kahlil Benson also competing for the role.The Chiefs often value competition to motivate guys, so maybe this offseason talk is just a ploy to fire up Moore and have him enter camp driven to win the job from the start.It’s still at least a little concerning for a win-now team that it is considering a pair of young undrafted free agents in Pole (2025) and Benson (2026) for such a vital piece on the front line.Kansas City tends not to mask things much during training camp practices with its rotations. We’ll definitely be watching to see who takes the first snap at right tackle next week — probably Moore — and then who sticks at that spot over the next few weeks.This much is certain: Moore still has work to do if he wants to prove he’s the best guy for the job.Defensive coordinator Steve Spagnuolo, left, needs as much time as possible to coach up rookie cornerback Mansoor Delane in training camp. (Colin E. Braley / Associated Press)Mansoor DelaneThere are two truths when it comes to rookie cornerback Mansoor Delane:1. Because the team traded up to select him with the No. 6 pick, he needs to be an immediate starter.2. He didn’t get off to a smooth start in spring practices, sitting out mandatory minicamp with a shoulder injury.The second note might seem minor, but it could quickly turn into a big deal if Delane shows any ill effects when he arrives this week. Defensive coordinator Steve Spagnuolo greatly values on-field reps for newcomers who are learning his complex scheme, and we can look to last season for a relevant data point.Free-agent cornerback Kristian Fulton missed part of training camp after right knee cleanup surgery, with Spagnuolo later saying it took a while for Fulton to earn trust and get caught up with the playbook. After that, Fulton struggled to see the field until deep into the season, when he held his own as a starter in the final two games.Reid, for his part, said in June he expected Delane to be ready to go for the start of camp. There’s also nothing wrong with early precaution, especially for a key player on the defense.None of that changes the reality, though. Delane faces pressure to perform right away after the Chiefs made their biggest draft bet on him.Felix Anudike-UzomahThe depth chart — for most of the offseason — made it seem like the defense could use another rotational player at edge rusher.That signing never came, which could lead one to believe the Chiefs have at least some hope that 2023 first-round pick Felix Anudike-Uzomah can be a contributor if he stays healthy.There’s no way to describe Anudike-Uzomah’s tenure as anything but a disappointment. The Chiefs have had to constantly backfill at edge rusher after he didn’t develop as anticipated, though the Kansas State product also hasn’t had the best luck with health. His latest setback came last preseason, when he suffered a hamstring injury that resulted in a season-long injured reserve stint.In the final year of his rookie contract, Anudike-Uzomah remains crazy young. He turned 24 in January, which means he actually was born about nine months after Chargers rookie edge rusher Akheem Mesidor, who was the 22nd pick in April’s draft.From that aspect, it’s not too late for Anudike-Uzomah to flash some of the potential he displayed in college. Either way, he’ll be one to watch in training camp to see if anything has clicked this offseason.His NFL future — with the Chiefs or otherwise — has a lot riding on these next few months.