INDIANAPOLIS — The Indianapolis Colts are in discussions about a contract extension with one of their biggest stars.

According to an NFL source, the Colts are working toward securing a long-term deal with running back Marlon Mack. Talks are expected to heat up later this month at the NFL Combine.

Mack, who turns 24 in March, is coming off of his first 1,000-yard rushing campaign and is eligible for a contract extension for the first time in his career.

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Set to make about $2.25 million in 2020, the final year of his rookie contract, Mack and the Colts are working on a deal that would keep him Indianapolis beyond next season.

In 2019, Mack led the Colts with 1,091 rushing yards and eight touchdowns on 247 carries (4.4 YPC) in a career-high 14 games.

That the Colts and Mack are discussing an extension should come as little surprise. Both sides expressed recent interest in striking a deal.

During his year-end news conference, general manager Chris Ballard praised Mack for his toughness after being asked about extensions to eligible Colts.

“Part of our offseason evaluation (is) -- we know, we're going to try to take care of our own -- so who are guys that we want to extend?” Ballard said, highlighting center Ryan Kelly before moving on to Mack. “Marlon, look, he easily could have missed more games (with a broken hand), but he didn't. He fought to get back in because he wanted to play.”

Mack, meanwhile, has made no secret about wanting to secure his long-term future in Indianapolis.

“I want to be right here,” Mack said in December. “I love it here. Love everyone here.”

At the beginning of the season -- just before Dallas Cowboys star Ezekiel Elliott signed his six-year $90 million extension -- Mack noted how important it is for running backs to secure guaranteed money early in their careers. Given the toll on their bodies over the course of a season -- getting hit hundreds of times -- the lifespan of most running backs isn’t very long.

"In this league, as a running back, you gotta strike fast," Mack said. "You don’t strike fast, that’s it for you. You're too old at (27). … Running backs, man, running backs don’t always get treated well. Running back is an important position. I hope people can learn that one day. I don’t know when it fell off (for us), but I need it to go back up (laughs). Hopefully it happens one of these days."

Fortunately for Mack, his resume doesn’t come with many of the warts other backs have on theirs. For one, he’s younger than most extension-eligible runners. Minnesota Vikings star Dalvin Cook -- who like Mack was drafted in 2017 -- will play next season at age 25, a year older than Mack.

Mack also doesn’t have the wear and tear many other backs do. His 587 NFL touches (535 rushes and 52 catches) pale in comparison to 2017 draftee and New Orleans Saints star Alvin Kamara (728), who also is eligible for an extension this offseason.

Of course, given Kamara’s All-Pro-level production, his contract will likely be bigger than Mack’s, though not by as much given the value teams place on having a lack of tread on the tires.

When sizing up what a Marlon Mack contract extension might look like, it is perhaps instructive to examine Lamar Miller, a back who produced similar numbers in his first three NFL seasons. Miller didn’t sign an extension, rather he departed via free agency in 2016 after four years in Miami, signing with the Texans for four years and $26 million ($14 million guaranteed). Miller was 25 years old when he left for Houston after having averaged 4.6 yards per carry in Miami with one 1,000-yard season on his resume.

Mack now has a 1,000-yard season on his resume while his career YPC is around 4.4. While Miller caught more passes than Mack, Miller had more wear on his legs (nearly 700 carries and more than 100 catches) than Mack’s 585.

Given the higher salary cap in 2020 (just above $200 million) vs. 2016 ($155.27 million), assume Mack could land a slightly more lucrative offer than Miller, but this would seem to be the ballpark in which he’s playing.

While it is not exactly common for teams to strike extensions at this time of the year, the Colts have done so recently. Last January, Ballard signed guard Mark Glowinski to a three-year, $18-million contract.

Follow IndyStar Colts Insider Jim Ayello on Twitter: @jimayello