The clock is ticking on the San Francisco 49ers’ Week 1 roster.Not only are there just 10 days before teams winnow their rosters to 53 players, but also three days after that, Sept. 2, the 49ers will take off for Melbourne, Australia. If you aren’t on the plane, you won’t play in the season opener against the Los Angeles Rams.Which means the 49ers have to get their Week 1 lineup in order far earlier than every other team, including the Rams, who will arrive in Australia shortly before the Sept. 10 game.With that in mind, the following are four unresolved positions heading into Thursday’s preseason game against the Los Angeles Chargers. A fifth competition, for the No. 3 quarterback, is on hold until Kurtis Rourke returns from a rib injury. Look for Adrian Martinez to take the bulk of the second-half snaps at SoFi Stadium.Wide receiverAs intriguing as top pick De’Zhaun Stribling has been this summer, we know he’s going to make the team and we know what his primary role will be — taking over Jauan Jennings’ former “F” or slot position.Jacob Cowing and Jordan Watkins, on the other hand, still are trying to carve out their roles. Cowing missed the 2025 season with a recurring hamstring issue and sat out last week’s preseason opener against the Tennessee Titans with a hip strain. He recently returned to practice and looked good, hauling in a pair of deep passes Saturday and Sunday.Wide receiver Jacob Cowing hasn’t played a regular-season game since the 2024 season finale against the Cardinals. (Christian Petersen / Getty Images)Watkins has been hot and cold in practice but was consistent against the Titans. He finished with six catches for 59 yards with another big reception called back due to a penalty.The 49ers are seeking “Z” receivers after Ricky Pearsall was lost for the season with a lingering knee issue. Deebo Samuel certainly will take over a portion of that role. But the 49ers have also been using him in the backfield as a so-called “wide back,” and at age 30 he’s not going to be close to an every-down player. Cowing and Watkins are trying to prove they can be San Francisco’s “Z” when Samuel is on the sideline or lining up elsewhere. They also are competing to be the team’s primary punt returner.A Week 1 roster spot seems to be slipping away from free-agent acquisition Christian Kirk, who was sidelined by a calf injury in the spring and who reinjured it in the first practice of training camp.“He hasn’t been ready to go, and he did it the first practice before we even got to team period, so I know he’s been extremely frustrated with it,” coach Kyle Shanahan said. “We love the guy so far, but hopefully he can have some better luck going forward here so he can get some reps out here.”Left guardRookie Carver Willis got the lion’s share of the first-team snaps at left guard in the most recent segment of practices, which means he might be in that role when the 49ers’ offense first takes the field Thursday.Willis never played guard in college, and, as expected, his initiation hasn’t always been smooth. Still, the 49ers seem determined to give him, Connor Colby and Robert Jones an equal shot of winning the starting job.If Willis works with the first-string offensive line as expected, he’ll at times be matched up against Chargers interior defensive linemen Teair Tart, Dalvin Tomlinson, Jamaree Caldwell and Justin Eboigbe. Eboigbe had six sacks last year and is having a strong camp.With Dominick Puni out with a concussion, look for Jones and Colby to get snaps at right guard.Defensive tackleThe first four defensive tackles on the 53-man roster likely will be Osa Odighizuwa, Alfred Collins, CJ West and Gracen Halton. If the 49ers keep five at that position as they often do, the last spot could go to one of three undrafted players:• Sebastian Valdez. A 2025 rookie, Valdez doesn’t have the length or the quickness of some of his position mates. Offensive linemen, however, hate going against him because he’s powerful and relentless. Though Valdez never played a snap last season, he was elevated from the practice squad for two games. That served as a nice pay bump and a signal the 49ers had plans for him this season.• James Thompson Jr. An undrafted rookie, Thompson’s combination of length and strength has allowed him to bully smaller offensive linemen. He led the 49ers’ interior defensive linemen with two pressures against the Titans and assisted on a sack by defensive end Ogbo Okoronkwo. Thompson, however, wasn’t as sturdy in the running game, which is often an issue for taller, long-legged defensive tackles.• Bryson Eason. He doesn’t flash as obviously as the other two. But Eason is built like a modern nose tackle with short, thick legs. He’s been hard to move in the running game and is the type of dirty-work player other linemen love to play beside.With West (concussion) and Halton (ankle) unlikely to play Thursday, the trio above figure to get plenty of work. The 49ers also recently signed another undrafted player, Evan Anderson, to round out the position.LinebackerDefensive coordinator Raheem Morris has been tinkering with the linebacker lineup since the spring. Fred Warner (middle) and Dre Greenlaw (weak side) are fixtures, of course. After them, the pecking order is in flux.For example, although Garret Wallow started at middle linebacker last week, Tatum Bethune, Jaden Dugger and Jalen Graham also have practiced at that spot.Dugger started the Titans game at strongside linebacker with Nick Martin playing the weakside spot. When the team switched to its nickel defense, Martin came off the field and Dugger moved to weakside linebacker.With every passing week, it seems more likely that Dugger, a fifth-round pick with only one college season at inside linebacker, will serve as the team’s third linebacker Week 1 against the Rams.“I saw a guy out there that looked like he belonged, first and foremost,” Morris said of Dugger’s outing against the Titans. “I saw a guy that showed great length. Saw a guy that showed great range and speed to be able to track tackles. Saw a guy out there that had a couple of learning things he needs to do and when he can take his risk, when he can absolutely let the trigger go. And I saw a guy that can really help himself by getting on and off blocks a little bit faster. Saw some good things. Saw some bad things. But overall, I was very pleased.”