The Kansas City Chiefs' 2015 National Football League (NFL) regular season cannot get any worse since after a 1–4 start, they also lost running back Jamaal Charles who is ruled out for the entire year with a torn anterior cruciate ligament (ACL). 

Charles suffered the injury while trying to make a cut in Sunday's 18–17 loss to the Chicago Bears, their fourth consecutive defeat of the season. 

The four-time Pro Bowler was stopped by the Bears' defense, and he went down holding onto his right knee while grimacing in pain. 

Charles was unable to put weight on the knee while being assisted off the field, and was attended by a medical staff on the sideline before going to the locker room, ESPN reported. 

Meanwhile, according to NFL.com, a magnetic resonance imaging (MRI) Charles underwent last Monday confirmed the injury and the Chiefs also made the announcement of him missing the entire season on the same day.

The last time Charles missed majority of a regular season was in 2011 when he did not play in 14 games due to the same injury to his left knee.

In five games played this season, the 28-year-old running back had 71 carries for 364 yards with four touchdowns. Along with his rushing game, he had 21 receptions for 177 yards and one touchdown. 

In Charles' absence, running backs Charcandrick West and Knile Davis will have to step up for Kansas City. 

Both have played in all five games of the Chiefs this season, with West having 12 carries for 48 yards and Davis with 11 carries for 27 yards and one touchdown. 

The loss of Charles is a huge blow for the Chiefs who started their 2015 season with a win over the Houston Texans before being plagued by four straight defeats to the Denver Broncos, Green Bay Packers, Cincinnati Bengals, and the Chicago Bears. 

Kansas City will have the chance to get back on the winning track when they take on the Minnesota Vikings in Week 6 on Oct. 18.