Seahawks quarterback Sam Darnold ruled out against the Cardinals with a quad injury

The Seattle Seahawks will be without starting quarterback Sam Darnold on Sunday against the Arizona Cardinals because of a quad injury.

Seahawks coach Mike Macdonald announced Wednesday that backup Drew Lock will step in for Darnold. Lock started one game earlier this season against the Cardinals in Arizona and played most of the season opener against the New England Patriots after Darnold suffered a glute injury.

Darnold's most recent injury came on the final drive of the Seahawks' 34-17 loss to the Chicago Bears on Monday night. He completed 17 of 34 passes for 188 yards, two touchdowns and one interception.

Macdonald said Darnold also cracked a rib early in the game against the Bears. But he will not go on injured reserve and will be evaluated on a week-to-week basis.

"So he’s playing the whole game without even making a thing of it and playing his tail off and competing,” Macdonald said. "I think it’s worth noting how tough this guy is. He’ll be back sooner than later, I’m sure.”

Darnold likely could continue playing with the rib injury, “but right now, it’s the quad that’s holding him out,” the coach said.

Lock has been dealing with a sore elbow that sidelined him for two games and Jalen Milroe has been the backup.

“The plan is for Drew to start, Jalen will be ready to back up. Drew’s still working back from his elbow so we’ll work through that process this week,” Macdonald said. “We’ll be getting both guys ready to play. Have full confidence in those guys.”

Lock has completed 35 of 48 passes this season for 422 yards and four touchdowns with no interceptions, including a three-touchdown performance in a 31-7 victory over the Cardinals in Week 2.

“I know Sam will attack his rehab, and Drew will step in and be the best version of himself for us, so I have all the confidence in him,” tackle Abe Lucas said.

Darnold has thrown for 1,478 yards and 10 touchdowns this season. He's been intercepted nine times.

The former USC quarterback did not miss a game last season as he led the Seahawks to a Super Bowl title. He threw for 4,048 yards with 25 touchdowns and 14 interceptions as Seattle won a franchise-record 14 regular-season games.

Macdonald said the Seahawks (4-4) may look to add another quarterback this week.

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