Who’s the next man up in the Seahawks’ secondary?

Here’s one sure way for the sun to set on coach Pete Carroll’s shiny disposition?

Ask him how his Seahawks are going to replace Richard Sherman for the rest of this season.

“I don’t know. I don’t even know how to address that right now,” the coach said in the stunned aftermath of Seattle losing its three-time All-Pro cornerback to a torn Achilles’ tendon during Thursday night’s win at Arizona.

When the Seahawks (6-3) play host to Atlanta (5-4) next Monday, it will be their first game without Sherman since 2010. They’ve played 105 consecutive regular-season games and 12 more in the playoffs — including two Super Bowls — with Sherman at left cornerback. He’s started every Seahawks game on that corner since Oct. 30, 2011.

Now there’s a gaping void.

“He’s just been a bastion of consistency, competitiveness and toughness through all of the stuff that we’ve worked through. It’s been awesome,” Carroll said. “It’s been hard. It’s been challenging. And he’s been extraordinary. Almost an iconic player in this league. … He’ll be with us every step of the way when he can, but we’ll miss the heck out of him.”

For years opponents have avoided throwing to Sherman’s side of the field, leaving the rest of the Seahawks’ defense to defend 75 percent of the field. Those days and weeks are over. At least for this year.

Jeremy Lane replaced Sherman for the final 1½ quarters in the win over the Cardinals. Seattle traded him to Houston a couple weeks ago while acquiring left tackle Duane Brown. But Lane had a bruised thigh and strained groin at the time and had missed two of the previous three games. When he failed his trade physical with Texans doctors, Houston sent him back to Seattle.

That could turn out to be a fortuitous break for the Seahawks.

Lane, 27, has started 19 games and played in 62 during his NFL career, all for Seattle. He’s been the Seahawks’ primary nickel back inside in recent seasons, and that role is why the team signed him to a four-year, $23 million extension before the 2016 season. He had a poor year in 2016, struggling both in coverage and with penalties.

Lane began this season as the starter at right cornerback, opposite Sherman. Then he got ejected early from the opener Sept. 10 at Green Bay for a pushing altercation with Packers receiver Davante Adams. On Oct. 1, after four starts, he strained his groin during the win against Indianapolis. Rookie Shaquill Griffin took Lane’s right-cornerback job and Justin Coleman his nickel spot.

Now, Lane’s healthy — and Sherman’s immediate replacement.

The Seahawks have other options. Again, none near Sherman’s level of performance or reputation.

DeShawn Shead could be an option. Eventually. He remains on the physically-unable-to-perform list following reconstructive knee surgery in January and a follow-up procedure this summer.

The Seahawks have until Nov. 21, the day after week 11 of the NFL season ends, to decide whether Shead is healthy enough to practice. If that answer is yes, Seattle has three weeks to either add him to the active roster or put him on injured reserve for the remainder of this season.

Byron Maxwell also is available. Another former Seahawks starting cornerback opposite Sherman, Maxwell was released by Miami on Oct. 24 and is a free agent. The 29-year old began his NFL career with Seattle the same season Sherman did, in 2011. He started 17 regular-season games and all six postseason ones for the Seahawks in the 2013 and 2014 seasons, including Super Bowls 48 and 49.

Then he signed a six-year, $63 million contract with Philadelphia before the 2015 season. That was the only season he played for the Eagles. He started 13 games for Miami last season and two this season before the Dolphins cut him.

At 6-foot-1, 198 pounds, Maxwell has the size and length the Seahawks like in cornerbacks, and he obviously knows Carroll’s step-kick technique off the line of scrimmage. Expect the Seahawks to at least call — or to have already called — to see how Maxwell might fit in.

Sherman turns 30 before next season, the last year of his contract. His salary for 2018 is scheduled to be a non-guaranteed $11 million, with a $13.2 million salary-cap charge.

Any chance the Seahawks might offer Sherman an extension before next season seems remote. The Achilles’ tear also greatly reduced his and Seattle’s leverage for any trade, which the Seahawks publicly entertained last offseason.

For now, the Seahawks seem likely to welcome Sherman back for 2018 at his current pay, to offer the opportunity to earn the extension and be motivated for a strong rebound season — plus possible free-agency riches in the spring of 2019 at age 31.

For now, there’s a gaping hole on the left side of the Seahawks’ defense that hasn’t been there since 2010. One that Matt Ryan, Julio Jones and the Falcons will be spending all this week preparing to target next Monday night.