Under general manager Brad Holmes and head coach Dan Campbell, the Detroit Lions’ offensive line has built a reputation as being one of the best in the league.

But if they want to keep it that way, they’ll have to keep investing resources in strengthening the unit. After veteran right guard Kevin Zeitler signed with the Tennessee Titans in free agency, there’s a clear argument for investing high-level capital into the position — especially after Campbell made it sound like left guard Graham Glasgow’s future as a starter is uncertain during the NFL’s annual league meetings last week.

It’s expected that Christian Mahogany, a sixth-round pick last year, will challenge for a starting guard position. But even if he wins a job, that still leaves one additional guard spot without a surefire starter.

If the Lions add an offensive lineman with their first-round pick, here are some likely candidates (listed alphabetically). One quick caveat: Guards typically aren’t considered a “premium position,” which means a good chunk of the candidates to go in Round 1 also have a decent amount of experience at tackle.

Tyler Booker, Alabama

Booker’s profile has risen since the NFL offseason officially began in February. Initially projected as a second- or third-rounder, there’s a real possibility he sneaks up into the first round, where he’s been a popular mock pick for the Lions (including our very own Mock Draft 1.0). He provided one of the best quotes of the NFL combine when he said his goal on the field was to make his opponents “not love football anymore.”

With his exceptional size and strength, Booker (6-foot-5, 325 pounds) started 25 games at left guard and one at left tackle over the last two seasons. In 2024, Booker was named a team captain and first-team All-American by CBS Sports and USA Today after allowing zero sacks and 10 pressures over 370 pass-blocking snaps.

Kelvin Banks Jr., Texas

Banks is a listed tackle with the potential to play guard at the next level. At one point, Banks was considered one of the top linemen in the draft, and that may still be the case — he is probably the least likely player from this list to be available at pick No. 28 — but his stock has been a little bit more volatile compared to the likes of Armand Membou (Missouri) or Will Campbell (LSU), who have stayed atop the consensus rankings for most of draft season.

Banks (6-5, 315) started 42 games at left tackle during his college career and was a first-team All-American in 2024 while also taking home the Lombardi Award (an award given out to the player who best honors the spirit of coaching legend Vince Lombardi). He was a stud in pass protection (eight pressures, one sack on 434 reps) and took his run blocking to another level last season, making him a versatile option if he falls in Detroit’s lap.

Josh Conerly Jr., Oregon

Conerly is another listed tackle who is sometimes projected as a guard. He was durable in college, starting 28 games at Oregon over his last two seasons for a team with national championship aspirations. He was a first-team All-Big Ten selection in 2024 as the Ducks marched to an undefeated regular season.

Conerly (6-5, 311) is athletic and strong, which should bode well for his ability to plug and play wherever his next team needs him. In 12 regular-season games, Conerly was tagged for just five pressures and one sack. The last time Holmes drafted a tackle from Oregon, things worked out pretty well.

Donovan Jackson, Ohio State

Jackson played nine games at left tackle in 2024 but most of his career at left guard (31 games), where he served as a three-year starter for the Buckeyes and earned All-Big Ten honors in each season. He fits a similar profile to Conerly as a guy who can likely become an immediate starter at guard while having upside as a reserve tackle.

Jackson (6-4, 315), a former five-star recruit, was named first-team All-Big Ten and a second-team AP All-American in 2024. His raw pass-blocking numbers (18 pressures, two sacks) aren’t as glitzy as some of the other players on this list, but he dealt with a hamstring injury throughout last season and received an 83.0 run-blocking grade from Pro Football Focus in his first season as a starter in 2022, which shows the potential to fit like a glove in Detroit’s smashmouth run game.

Grey Zabel, North Dakota State

Zabel quieted concerns about his FCS pedigree with a terrific performance at the Senior Bowl, where he was voted the practice player of the week by NFL executives in attendance. Since then, his stock has been sky-high; he enters the draft with an extremely high chance to hear his name called in Round 1. If he slips into the mid-to-late 20s, he’d be a great succession plan for a Lions O-line that’s aging in some parts.

Zabel (6-6, 312) played left tackle all of last season but has significant experience at guard. Some analysts are even projecting him as a center, a testament to his seamless versatility that he displayed at Senior Bowl practice in Mobile, Alabama. In 809 pass-blocking snaps over the last two seasons, Zabel allowed just 16 pressures and three sacks. He was a two-time FCS national champion with the Bison and named an FCS first-team All-American in 2024.