INDIANAPOLIS -- While the Indianapolis Colts were reestablishing their identity with the running game, they lost their most important running back.

Marlon Mack's fractured right hand, suffered in the second half of Sunday's 33-13 victory over Jacksonville, will sideline him indefinitely. Now the Colts are looking to replace him during a short week of preparation before Thursday’s battle for first place in the AFC South against the Houston Texans.

"That is kind of a week-to-week, play-by-play situation," Colts coach Frank Reich said about replacing Mack. "We'll miss Marlon, obviously. He is having a great year, but I feel very confident in all three of those guys."

The Colts have to find a way to make up for losing a player who has rushed for 862 yards and is averaging 4.5 yards per carry this season.

Jonathan Williams and Jordan Wilkins will get the first crack at replacing Mack and his 19.2 carries per game, with Nyheim Hines getting some snaps on third down and passing downs.

Things aren't going to change for the Colts as far as the game plan goes. They're at their best when they run the ball while sprinkling in the passing game. The Colts rushed for 264 yards Sunday, their highest total since 2004. It also marked the sixth time this season that they've rushed for at least 127 yards in game.

"We definitely needed a game like that," guard Quenton Nelson said. "We need to carry this momentum into [Houston] and the weeks that follow."

Wilkins and Hines, both second-year players, have been part of the running back rotation since they joined the team. The unfamiliar name in the group -- up until Sunday against the Jaguars -- was Williams. He went into the game having rushed for just 1 yard this season and his career high in yards for a single game was just 26 yards while with the Buffalo Bills in 2016. Since then, Williams has played for three different teams, splitting time between the practice squad and the inactive roster for the past two seasons with the Colts.

Reich and general manager Chris Ballard used to sit in the coach's office and talk about the runs Williams had while being a part of the scout team in practice.

The talent was there, but the roster spot just wasn't there for him to show it on game days.

But things changed for Williams against the Jaguars, partially because Wilkins was inactive with an ankle injury and then Mack went out with the broken hand. Williams rushed for 116 yards and a touchdown on just 15 carries to go with one reception for 31 yards.

"He comes in and he works hard," quarterback Jacoby Brissett said. "He's always ready. Every time we're doing things he's always eavesdropping, but I guess it paid off. He did a heck of a job running the ball and understanding the runs that we had. For a guy that probably didn't get as many reps, I think he understood the runs and made some great situational plays, going down, staying in bounds, keeping the clock rolling and not taking any unforced errors. He did a great job in protection and he gets rewarded like he did."

Williams doesn't hesitate in saying it has been tough having to sit and wait his turn to get some snaps. Sunday marked the first time he got more than five carries since Dec. 29, 2014, when he ran for 105 yards against Texas in leading Arkansas to a victory in the Texas Bowl. Williams didn't play in 2015 because of a foot injury.

"Every day to get to this level, you have to have that competitive nature," Williams said. "Have to not want to be complacent. Have to want more to get this level. [It's] hard to sit and watch. But I'm a team guy. I'm not a selfish guy. ... This might sound crazy, but every day I went into it like I like was a starter at practice. I would put myself into the game literally, mentally. I've done this mentally before."

Now the Colts will see if Williams can do it again when first place in the division is on the line Thursday against the Texans.