Rookie left guard Grey Zabel suffered a knee injury in the closing minutes of the Seattle Seahawks’ 21-19 loss to the Los Angeles Rams on Sunday afternoon.

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Zabel, the No. 18 overall pick in April’s NFL Draft, was injured on Kenneth Walker III’s 1-yard touchdown run that pulled Seattle within two points with 2:23 to play. Zabel pulled out to the right to help clear space for Walker, but left tackle Charles Cross got pushed Zabel’s left knee.

Trainers tended to Zabel on the ground before helping him limp off the field. Second-year pro Christian Haynes, who was activated off injured reserve on Saturday, replaced Zabel at left guard for Seattle’s final drive.

After the game, Seahawks head coach Mike Macdonald said Zabel will need imaging to determine the severity of the injury.

“It’s his knee,” Macdonald said. “No update. We’ll get it imaged and see what’s going on.”

Zabel has lived up to the billing as a first-round pick, serving as a steady force up front while starting all 10 of Seattle’s games at left guard.

Heading into this week, the 6-foot-6, 316-pound North Dakota State product ranked No. 1 among all interior offensive linemen in ESPN’s run block win rate. He also was tied for 16th out of 84 guards in Pro Football Focus‘ pass blocking efficiency metric and hadn’t allowed a sack in 252 pass block snaps.

The Seahawks are already missing starting center Jalen Sundell, who they placed on IR Saturday with a knee injury. Sundell, who played alongside Zabel at North Dakota State, started each of Seattle’s first nine games prior to landing on IR. Backup center Olu Oluwatimi started on Sunday.

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