The Indianapolis Colts (2-1) are heavy favorites taking on the Oakland Raiders (1-2) at Lucas Oil Stadium on Sunday, but there are still some concerns to keep an eye on.
The Colts have enjoyed a two-game winning streak since opening the season with a loss while the script is flipped for Raiders—who opened the season with a win but dropped their last two games.
As we detailed reasons for optimism in this matchup, here are three causes for concern in Week 4:

Darius Leonard, other injuries impact the Colts
With the injury designations out, the Colts will officially be without the All-Pro linebacker for the second week in a row as he remains in the league’s concussion protocol. While the Colts got by against a tough Falcons offense without him in Week 3, there is still concern with Leonard missing.
We knew safety Malik Hooker would be ruled out after tearing his meniscus, and second-year defensive tackle Tyquan Lewis is also out with an ankle injury. The Colts could also be without T.Y. Hilton (quad) and defensive end Jabaal Sheard (knee) for the matchup.
The Colts are heavy favorites in the game, but the injuries to some significant contributors shouldn’t be overlooked.

Josh Jacobs is due for a breakout
The first-round pick for the Raiders has been a focal point in the offense and while he hasn’t had a true breakout game, there is one coming. He’s simply too talented and gets too much work for it to not happen. It could happen Sunday against a Colts defense that has struggled against the run.
Even though the Colts haven’t allowed a 100-yard rusher yet this season, Jacobs presents a challenge. Through the first three games of the season, the Colts have allowed 5.42 yards per carry to opposing backfields while allowing a rushing touchdown in two of the games.
Without their best run stopper in Darius Leonard again, the Colts must make sure Jacobs is kept in check, or else that breakout game is certain to happen.

Darren Waller also presents a challenge
After a long road back to the NFL, Waller is taking the league by storm. Converting from wide receiver to tight end, Waller is among the league leaders at a position the Colts have struggled defending since the start of the 2018 season.
Waller is an athletic pass catcher that has an innate ability to wreak havoc after the catch. He will be a tough matchup for whichever defender lines up against him—with rookie safety Khari Willis being a candidate.
The Colts typically struggle covering tight ends, and they just allowed six receptions for 66 yards and two touchdowns to Austin Hooper. Though most of the matchups favor the Colts, this one potentially does not.