SANTA CLARA — Safety Eric Reid is expected to debut with the 49ers starting defense Sunday night. He could stick there for, oh, the next decade.

Wait, a rookie starter under defensive coordinator Vic Fangio? That hasn’t happened since Fangio arrived with coach Jim Harbaugh two years ago.

“He’s done well all camp,” Fangio said. “We’ll probably start him in this game coming up, and we’ll see how he does with that.”

The 49ers host the Minnesota Vikings on Sunday night in each team’s third exhibition. With this being the proverbial dress rehearsal for the Sept. 8 regular-season opener, Reid might get tested deep by the Vikings’ new receivers and also might encounter reigning league MVP running back Adrian Peterson.

“Maybe I can tackle him — get a solo tackle — and have a picture,” Reid said. “That’s something I’ll definitely keep.”

Reid has looked like a keeper since the 49ers traded up to draft him 18th overall in April. The 49ers’ previous two first-round picks, Aldon Smith and A.J. Jenkins, took vastly different paths after their selections.

Whereas Jenkins got traded Monday to Kansas City after a zero-catch rookie season, Smith is one of the NFL’s premier pass rushers. That said, Smith was a situational pass-rusher as a rookie and didn’t became a full-time starter until last season.

“Nothing was given to Aldon that (rookie) year, and nothing’s going to be given to Eric this year,” Fangio said last month at the start of training camp. “He’s got to go out and earn it.”

Reid became a starter at LSU for his final three games as a freshman, and he stayed in that role the next two years en route to All-America honors.

“He’s real smart, and he’s going to be a big help for us,” cornerback Carlos Rogers said. “How well can he hit? Real good. There’s something about those LSU safeties — they all can hit.”

So can Dashon Goldson, the 49ers’ physically intimidating starting safety the past four seasons who left in March to sign a $41.3 million free-agent deal with the Tampa Bay Buccaneers.

Reid has shown potential to fill Goldson’s hard-hitting role and seems unfazed by top-pick pressure. Rogers, a 2005 first-round pick of the Washington Redskins, is curious how Reid will handle that status as the season unfolds.

“The time will tell when we get in game situations and you’re not hitting people like Dashon did and you’re not getting interceptions,” Rogers said. “Not saying he won’t, but if this happens, you know people expect him to do what Dashon did.

“Dashon was an All-Pro player,” Rogers continued. “It’s rare to see rookies come in and be an All-Pro player, just learn everything right then and there. But we’re all here to help him get better as we get better.”

Former Rams safety Craig Dahl drew the start next to Donte Whitner in the first two exhibitions. But Dahl played only 26 snaps on defense whereas Reid played 85.

Reid made a couple big hits in the exhibition opener against the Denver Broncos, and his third-down blitz pressured Alex Smith into an incompletion Friday at Kansas City.

“I have high expectations of myself,” Reid said. “There’s always the expectations of the media and fans, but I don’t look too much into that. I’m self-motivated.”

The 49ers’ quarterback stable grew to five with the addition of Seneca Wallace on a one-year contract. Wallace, 33, did not play last season after debuting with the Seattle Seahawks from 2005-09 and backing up current 49er Colt McCoy with the Cleveland Browns in 2010-11. Wallace has appeared in 62 games and is 6-15 as a starter. He had his contract terminated by the New Orleans Saints on Monday. McCoy, Scott Tolzien and rookie B.J. Daniels are also vying for backup roles behind Colin Kaepernick. McCoy’s grip on the No. 2 role, which he inherited upon his April 1 arrival in a trade with Cleveland, has loosened. Through two exhibitions, he is 6 of 13 for 76 yards with two interceptions and a 25.3 rating.

Wide receiver Ricardo Lockette was released despite his close ties with Kaepernick. A member of last season’s practice squad, Lockette had no receptions, no targets and one special-teams tackle this exhibition season. He was housemates with Kaepernick and accompanied him on offseason journeys, such as their spring workouts in Atlanta and a trip last month to the ESPY Awards.

Safety Darcel McBath, primarily a special-teams contributor during last season’s Super Bowl run, was placed on injured reserve because of an apparent foot injury. McBath had a fumble recovery last season and ranked second on the 49ers’ special-teams points chart.

Linebacker Joe Holland was claimed off waivers from the Tampa Bay Buccaneers. Holland joined the 49ers last year as an undrafted free agent from Purdue. After the 49ers cut him Aug. 31, he spent time on the Miami Dolphins and Buccaneers practice squads.