ESPN Seahawks reporter Brady Henderson breaks down how Seattle will be affected by All-Pro S Kam Chancellor likely missing the rest of the season with a neck injury. (1:36)

Seattle Seahawks strong safety Kam Chancellor likely is headed to injured reserve with a neck injury and will miss the remainder of the season, a source confirmed to ESPN's Josina Anderson on Saturday.

Coach Pete Carroll, however, said the Seahawks are still evaluating the injury and aren't ready to declare Chancellor out for the season.

"We're still looking at what our options are, and we'll continue to do that and evaluate what's going on," Carroll said Saturday. "We're working very closely with him on that."

The eight-year veteran left last week's game against Arizona with a neck injury on the Cardinals' final possession. Carroll said earlier this week that Chancellor suffered neck stingers but was still undergoing testing.

Asked Saturday if there's concern it could be more serious than a season-ending injury, Carroll said, "We'll wait and see."

Chancellor posted a message on Twitter on Saturday, saying, "The best is yet to come."

The best is yet to come. Thank you for all the prayers and messages. Gods Grace is all you can ask for 🙏🏿🙏🏿🙏🏿 — The Enforcer (@Kam_Chancellor) November 18, 2017

"Kam is still looking to play [next season]," the source told Anderson. "Neck injuries are serious. ... [Chancellor] will continue to be evaluated in hopes of getting him ready next year."

The Seahawks have officially ruled Chancellor out of Monday night's game against the Atlanta Falcons.

The NFL Network was first to report Saturday that Chancellor likely would miss the rest of the season because of the neck injury.

Chancellor is under contract through 2020 after signing a three-year extension during the summer that's worth up to $36 million. Since 2014, he has missed nine games to injuries and two others while holding out.

The four-time Pro Bowl selection, who has 49 tackles and one forced fumble this season, did not practice Thursday or Friday. The hard-hitting safety has 12 career interceptions.

Bradley McDougald, who is Seattle's primary backup at both safety spots and has started the past two games at free safety, likely will start for Chancellor at strong safety against the Falcons.

The Seahawks (6-3) are one game behind the NFC West-leading Los Angeles Rams and are currently the sixth seed in the NFC playoff standings -- one game ahead of four teams.

Seattle's secondary already is without Pro Bowl cornerback Richard Sherman, who suffered a ruptured Achilles tendon in last week's victory over Arizona and is out for the season. Star safety Earl Thomas is expected back this week from a hamstring injury, and Jeremy Lane will start at left cornerback in place of Sherman.

In addition to McDougald and Lane, Carroll singled out rookie Shaquill Griffin and Byron Maxwell for stepping up when they were needed.

"We couldn't be more fortunate in that the guys that get to step up for those guys," Carroll said Saturday. "You can't replace either one of those guys directly. They've been here a long time, they've done so much, they stand for so much. ... We just feel fortunate that we've been able to respond in this manner. A lot of teams aren't able to do it like that. So we'll see how it goes, but we expect those guys to play really well.

"The true test is when we come back and play a couple more games and see how we're doing and see how it all holds together like we want, but we couldn't be happier with the guys that are jumping in there. These guys are ready to play football. They've been playing, they know how to play the game, and the experience they bring really helps smooth the transition. So we'll see what happens."

ESPN's Brady Henderson contributed to this report.