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The 49ers come to town this week, starting with joint practices Wednesday and Thursday against the Vikings at TCO Performance Center before Saturday's preseason game at U.S. Bank Stadium.

Throughout training camp, head coach Kevin O'Connell and his assistants have pointed to the joint practices as more critical for player evaluations. Starters will get to face another team without live tackling, dampening the threat of injury that kept nine prominent players – from receiver Justin Jefferson to edge rusher Danielle Hunter – from playing in the preseason opener in Las Vegas.

According to O'Connell, how starters are evaluated in joint practices will determine who sees action in the second exhibition on Saturday. Quarterback Kirk Cousins is expected to return from a mandatory five-day quarantine after testing positive for COVID-19 last week.

"We're going to see how these practices go against the 49ers," O'Connell said after the Vikings' 26-20 loss to the Raiders on Sunday. "See what kind of reps we can get in. We got two really good scheduled days of work against a really good football team. So, we'll come out of that, kind of assess what that weekend is going to look like."

The next few days also offer prime opportunity for players competing for roles. Here are five position battles to watch against the 49ers.

Backup quarterbacks

Kellen Mond showed the decisiveness coaches have sought from the second-year quarterback in a strong second half against the Raiders. Carrying that over this week could help him leapfrog veteran Sean Mannion, who started in Las Vegas, for the backup job. Neither quarterback has had a great camp so far, so Mond and Mannion are not only competing against each other, but also trying to keep the front office from looking elsewhere for backup help. In come the 49ers and last year's third-ranked defense.

Second cornerback

Third-year cornerback Cameron Dantzler has broken up passes and garnered praise from coaches during camp, keeping him atop the depth chart over second-round draft pick Andrew Booth Jr. They didn't see many passes thrown their ways against the Raiders, but both were penalized in coverage. Booth has seen a lot of yellow; the rookie needs to show he can adhere to stricter coverage rules in the NFL. He's got the talent and confidence to eventually start should he prove to be reliable.

Safeties

Camryn Bynum, the second-year safety, is another young defender who has made a handful of plays on the ball in camp. He's so far taken the lion's share of first-team reps next to Harrison Smith, ahead of first-round pick Lewis Cine. But Cine knows "there's a place for me" in coordinator Ed Donatell's defense, which is expected to feature various packages with five or six defensive backs. How much Cine plays right away remains to be seen. Bynum appears to have earned a role whether he's starting or not.

Right guard

Veteran Jesse Davis started at right guard against the Raiders and played just eight snaps before the starting offensive line was pulled from the game. Second-round pick Ed Ingram replaced him and appeared to fare well in 30 snaps, especially as a run blocker. Ingram got hands on two defenders, including walling off a Raiders linebacker, during Ty Chandler's 14-yard run in the second quarter. The Vikings need to shore up the interior line, and Ingram appears to be ascending as the competition ramps up.

Backup receivers

Bisi Johnson, the reliable fourth-year receiver, started opposite K.J. Osborn against the Raiders. He seems to have a leg up as the fourth receiver over Ihmir Smith-Marsette, Albert Wilson, Jalen Nailor, Dan Chisena and Trishton Jackson. The team needs to pinpoint who can fill the fifth and sixth spots, assuming they keep six receivers on the 53-man roster. Smith-Marsette had an uneven preseason opener, dropping a pass and a punt return. Special teams roles could be a tiebreaker in this logjam at the bottom of the depth chart.

The Vikings' joint practices with the 49ers at TCO Performance Center in Eagan are open to the fans. Tickets are $5 for adults; kids 17 and under are free. Gates open each day at 9 a.m, with practice from 10 a.m. to noon.