Dallas Cowboys running back Ezekiel Elliott will be absent for the game against the Atlanta Falcons, although the team has not disclosed the reason

Dallas Cowboys running back Ezekiel Elliott will not be traveling to Atlanta and will miss Sunday’s game for reasons the team has not revealed.

This announcement on Saturday marks the first time in eight seasons, across two terms with the Cowboys, that Elliott will miss a game for reasons other than injury, suspension, or in games that didn’t require their top running back.

According to ESPN, sources that wished to remain anonymous reported that the absence is due to disciplinary reasons.

Elliott, who has won two rushing titles and was the fourth overall pick in the 2016 draft, returned to the Cowboys this offseason after spending a year with the New England Patriots. The Cowboys let Elliott go last season to save money.

At 29 years old, Elliott’s performance this season has not been strong. He is averaging a career-low of 3.1 yards per carry, totaling 149 yards on 48 carries. He has scored the only two rushing touchdowns for the NFL’s least effective rushing offense. The Cowboys (3-4) are averaging just 74 rushing yards per game.

Dalvin Cook has been moved up from the practice squad for the second week in a row and will back up Rico Dowdle against the Falcons (5-3). Dowdle missed last week’s 30-24 loss to San Francisco because he was sick.

Elliott won both of his rushing titles in his first three seasons with the Cowboys. He led the NFL in rushing yards per game in another year when he was suspended for six games due to domestic violence allegations.

In his first seven seasons with the Cowboys, Elliott missed only five games outside of his suspension—three due to injuries and two regular-season finales when the Cowboys had already secured a playoff spot.

Elliott’s touchdown last weekend against the 49ers was his 70th rushing touchdown with Dallas, putting him two behind Pro Football Hall of Famer Tony Dorsett for second place on the team’s all-time list. NFL all-time rushing leader Emmitt Smith, also a Hall of Famer, holds the records for both rushing yards and touchdowns for the Cowboys.