Going into 2019, we know the primary suspects for the best running backs in fantasy football. The Saquon Barkleys, the Christian McCaffreys, the Ezekiel Elliotts (if he actually plays), etc.

But what about the halfbacks who may not be taken that early but can provide great value later on? In other words, who are the biggest sleeper running backs in fantasy football heading into 2019?

Here are five sleeper backs to consider in fantasy football this season:

Austin Ekeler, Chargers

5. Austin Ekeler, Los Angeles Chargers

With Melvin Gordon holding out with no end in sight, Austin Ekeler may be the Week 1 starter at running back for the Chargers next month, which would skyrocket his value.

Of course, there is a lot of uncertainty here, as we don't know what is going to happen with Gordon, but given that Gordon does seem prepared to pull a Le'Veon Bell, Ekeler could emerge as a strong candidate.

Ekeler was really solid in the No. 2 role this past year, totaling 554 yards and three touchdowns on the ground while averaging 5.2 yards per carry. In addition, he hauled in 39 receptions for 404 yards and three scores, so he is also versatile.

Again, this all depends on Gordon, but if he sits, Ekeler could be a great option.

Ito Smith, Falcons
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4. Ito Smith, Atlanta Falcons

Ito Smith had a rather rough rookie campaign this past year, rushing for 315 yards and four touchdowns while averaging a meager 3.5 yards per carry, but there is reason to like him heading into 2019.

First and foremost, he is going into this season as the clear-cut No. 2 back. Remember: last year, both Devonta Freeman and Tevin Coleman were ahead of him on the depth chart, so when Freeman got injured, Smith wasn't completely ready to shoulder the load of a No. 2.

This time around, he should be prepared for it, as Coleman signed with the San Francisco 49ers this offseason.

Smith was a monster at Southern Mississippi and also possesses great hands in addition to his running ability, so he could be a nice all-around threat to pick up in the later rounds.

Royce Freeman, Broncos

3. Royce Freeman, Denver Broncos

Phillip Lindsay may have stolen the show for the Broncos this past year, but it seems evident that Denver views Royce Freeman as its guy moving forward, as all signs are pointing to Freeman getting more carries than Lindsay in 2019.

Plus, with the declining Joe Flacco under center and an iffy receiving corps, the Broncos will probably pound the football quite a bit this season, meaning Freeman could see a lot of action.

He carried the ball 130 times for 521 yards and five touchdowns in his rookie year in 2018, but don't be surprised to see those numbers jump significantly this year. It would be nice if Freeman could catch some passes, though, as he logged just 14 receptions this past year.

Aaron Jones, Packers

2. Aaron Jones, Green Bay Packers

I'm not even sure you could consider Aaron Jones to be a “sleeper” anymore, because most people seem to be on to him, but he won't be one of the top running backs chosen, so therefore, he belongs on this list.

Jones has been one of the league's most efficient runners over his first two NFL seasons, averaging 5.5 yards per carry in both years.

Of course, the main issue with Jones is injuries, as he was limited to 12 games in each of his first two seasons as a result of knee issues. Heck, had it not been for a sprained MCL this past year, Jones may very well have rushed for 1,000 yards, as he totaled 728 while missing four games.

New head coach Matt LaFleur also seems prepared to utilize Jones, so be ready for a potentially big year.

Marlon Mack, Colts

1. Marlon Mack, Indianapolis Colts

In the same vein of Jones, I'm not sure Marlon Mack is a sleeper at this point, but again, because there will likely be a bunch of running backs drafted ahead of him, he deserves a spot here.

The recent development with Andrew Luck's calf and ankle issues make Mack an even better play here because if Luck can't go in Week 1 or is out for even longer, Mack will see a ton of carries early.

This is a guy who rushed for 908 yards and nine touchdowns in just 12 games this past season, so if he can stay on the field, he could be a home run pick.

The only drawback with Mack is his ineffectiveness as a receiver, as he has caught just 38 passes over his first two NFL seasons.