SEATTLE -- It took a handful of critical plays to help the Seattle Seahawks overcome yet another slow start on offense Sunday night.

Cornerback Justin Coleman, running back J.D. McKissic and defensive end Marcus Smith delivered.

Wait, who?

Indeed, the Seahawks got major contributions from some unlikely sources in their 46-18 win over the Indianapolis Colts. Coleman returned his first career interception for a touchdown, Smith had a hand in another defensive score, and McKissic found the end zone twice to help the Seahawks turn a halftime deficit into a runaway victory.

"Oh, you're freakin' juiced for them," cornerback Richard Sherman said when asked what it's like for backups to step up the way Coleman, Smith and McKissic did Sunday night. "You're freakin' juiced, not just because it helps your team, but because you're happy that all their hard work is paying off. They're your teammates, so it's like you're brothers."

Seattle's victory may have come at a cost. Standout rookie running back Chris Carson, who has started all four games this season, was carted off the field in the fourth quarter with an air cast on his left leg. Coach Pete Carroll described it as a "significant" ankle injury but didn't have a timetable for how long Carson might be sidelined, saying the team won't know until Carson undergoes further testing.

It turned out to be another dominant performance under the lights by the Seahawks. They improved to 20-3-1 in prime-time games since Carroll arrived in 2010, including 13-1 at home. In those 24 games, Seattle has outscored opponents 627-316.

But the Seahawks' latest prime-time blowout started off on the wrong foot.

Starting cornerback Jeremy Lane left the game for good after suffering an injury on the opening series; it was initially called a hip injury but Carroll said afterward it's a groin injury. That forced rookie Shaquill Griffin to go from the third cornerback to the starter opposite Richard Sherman, which bumped Coleman into the nickel role.

Coleman read Colts quarterback Jacoby Brissett and jumped an out route, picking it off and returning it 28 yards for a touchdown that gave Seattle a 10-2 second-quarter lead. Coleman and Brissett were teammates with the New England Patriots, who traded Coleman to Seattle before the start of the season for a seventh-round pick.

The Seahawks scored another defensive touchdown in the third quarter when Smith hit Brissett as he was throwing, causing a fumble that middle linebacker Bobby Wagner returned 21 yards to the end zone for a 32-18 Seattle lead. Smith, a former first-round pick by the Philadelphia Eagles, played extensively Sunday after starter Cliff Avril left the game in the first half with a neck injury.

McKissic scored on a 30-yard run in the third quarter and then caught a 27-yard touchdown pass in the fourth quarter, a perfect illustration of his versatility as a running back/wide receiver.

"I was kind of thrilled by the way J.D. McKissic jumped on the scene," Carroll said. "This guy has been practicing great for us; we've seen it all along. We've seen nothing but good stuff from him. He's been a great kid; he just hasn't had his shot yet."

The Seahawks outscored the Colts 36-3 in the second half. According to ESPN Stats & Information, that marks Seattle's most second-half points and biggest point differential in a second half in franchise history. The Seahawks needed that strong finish after their offense produced only five first downs and 140 yards through the first two quarters. Indianapolis, which entered the game as a 13-point underdog, led 15-10 at halftime, leading to boos from some of the CenturyLink Field crowd.

McKissic was active for the first time this season with C.J. Prosise out due to an ankle injury. Thomas Rawls was a healthy scratch, while Eddie Lacy played for the first time since Week 1. Lacy led the team with 52 yards on 11 carries as the Seahawks ran for a season-high 194 yards.

If Carson's injury is as serious as it looked, the Seahawks will need those four to step up in his absence -- starting next week against the division-leading Rams in Los Angeles.