The Jacksonville Jaguars will be without star running back Leonard Fournette heading into their Week 5 matchup against the undefeated Kansas City Chiefs. Fournette was officially ruled out of Sunday's game today and is "out indefinitely" after aggravating a right hamstring injury during Sunday's win agains the New York Jets.

According to ESPN, head coach Doug Marrone said he's unsure when the team will be able to determine how much time Fournette will miss.

"I really don't know," Marrone said. "Believe me, if I knew exactly what the deal was and I could tell you -- three [games], six, 10, IR, whatever -- I would. I just don't know. Those injuries are tough. We talked about it by position. We talked about it by player. We've talked about it every other way. "I thought he was looking good. ... You guys see him working [in practice] ,but it's different when you're playing a game. The game's different."

Fournette originally injured his hamstring during the first half of the team's season opener and has missed games against the New England Patriots and Tennessee Titans. 

After this Sunday's much anticipated showdown agains the Chiefs at Arrowhead Stadium, the Jags (3-1) will head to Jerry's World to take on the 2-2 Dallas Cowboys. According to ESPN's Michael DiRocco, "it's not out of the question that Fournette could be held out until their Week 10 game at Indianapolis on November 11."