The Seahawks open their regular season on Sunday with a tough road test against the Indianapolis Colts, an 11-win team last season and one that features big challenges on both sides of the ball.

"We're getting ready for a really good club, a well-oiled machine," Seahawks coach Pete Carroll said. "All phases of the game are good so it's a championship matchup for us, we have to play championship football."

If the Seahawks are going to open the season with a win on the road for the second straight year, these are three matchups that could make the difference in Sunday's game at Lucas Oil Stadium:

1. Unknowns on offense vs. the ability to adjust on defense.

The Seahawks come into this season with a new offense having made a change at offensive coordinator, and the hope in Seattle is that the offense will not only thrive under Shane Waldron, but also that, to start the year at least, it might confuse opposing defenses that have not yet gotten a look at Waldron's offense.

Sure, Waldron figures to bring with him from Los Angeles some elements of the Rams offense, but he'll also mix in some of his own ideas, as well as elements of the previous offense that worked well for Russell Wilson and company, so the Colts defense won't know exactly what to expect on Sunday, particularly with the Seahawks resting Wilson and most of the other offensive starters for the entire preseason.

The Colts, meanwhile, aren't starting over on offense, not with Frank Reich still calling the shots heading into his fourth season as the head coach, but the offense does figure to look different with a new quarterback running things. Last season the Colts had Philip Rivers at quarterback, but he retired in the offseason, and Indy replaced him with former Eagles starter Carson Wentz, who enjoyed his best seasons with Reich calling plays as the Eagles' offensive coordinator.

"The personnel around him is going to be different, but I would assume the offense is going to be pretty similar to the (Eagles)," linebacker Bobby Wagner said. "I think that's the reason he came back to Indy is because of the success he had with Frank Reich. You'll see a lot of RPO's, a lot of movement. They have a great running game that's going to complement some of their play action stuff. I wouldn't be surprised if they try to move him out of the pocket, unless he's still hurt, and get the ball out of his hand and he's going to find receivers. He's really good at getting the ball out of his hands, making reads. It'll be a lot different than the film that we're watching with Philip Rivers, because he's had so much experience. He's calling out plays and things of that nature. I think it'll be fun. You definitely have to be conscious of him taking off if he doesn't have anything."

Whichever team makes the necessary adjustment and handles the element of the unknown best could very well be the team that comes out on top.

2. All-Pro defensive tackle DeForest Buckner vs. Seattle's interior line.

The Seahawks added guard Gabe Jackson via an offseason trade to help bolster their interior line, and Jackson, fellow guard Damien Lewis and center Kyle Fuller should have their hands full on Sunday with All-Pro defensive tackle DeForest Buckner.

Buckner, who Seahawks fans know well from his four seasons in San Francisco, had 9.5 sacks last season, his first with the Colts, as well as 58 tackles, 26 quarterback hits, 10 tackles for loss and two forced fumbles.

"He's a very tall guy with long arms, but he plays with very good leverage," Seahawks tackle Duane Brown said. "I think he's like 6-7 or 6-8, but he plays with good leverage, uses his hands, strong, plays hard, and he has good instincts on how you are going to try to block him. He rushes accordingly, so we have to have a gameplan for him, because he will be lined up on the inside most of the time. It's a good first challenge."

3. A dynamic Colts running back duo vs. Seattle's run defense.

Jonathan Taylor, a second-round pick last year, was held under 70 rushing yards in eight of his first nine games, but finished his rookie year on a tear, gaining 90 or more yards in four of his final six, including 150 yards and two scores in Week 14, and 253 yards and two scores in Week 17, giving him a total of 1,169 yards and 11 touchdowns for the season.

Taylor, who had 685 yards after contact last season, features a rare combination of speed and power, and by himself he would make for a formidable challenge for any run defense, but what makes the Colts' run game particularly dangerous is the combination of Taylor and Nyheim Hynes, a small but explosive back who has 170 receptions over his first three seasons, including a team-leading 63 last season.

Seattle's defenses have consistently been among the best in the NFL under Pete Carroll, but Bobby Wagner and company will have their hands full containing the running game this weekend.

"Both of those guys are an explosive play waiting to happen with the speed that they have," Carroll said. "Sometimes guys run really good times and you don't notice it, but you notice with these two guys. Both of these guys have rocket acceleration, are strong enough to break tackles, and make the most of good play that isn't necessarily a good play. I think, I'm not sure about this but you guys could verify it, Jonathan had like 600 yards after contact last season. That's crazy numbers, half of his rushing yards were after he was hit and had a chance to get tackled but he didn't let it happen. Those are fantastic players."