JACKSONVILLE, Fla. -- Jacksonville Jaguars running back Leonard Fournette will be out indefinitely after aggravating a right hamstring injury during the team's victory over the New York Jets on Sunday.

Coach Doug Marrone also 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."

Marrone was asked if short-term IR was a consideration, but he said he mentioned that as a way to illustrate that he was unable to be definitive about how long Fournette will be out. If the team were to place Fournette on short-term IR, he could not practice for at least six weeks from the date he was placed on IR and could not return to the active roster for at least eight weeks.

Fournette had an MRI on Sunday following the Jaguars' 31-12 victory at TIAA Bank Field, and Marrone said the injury does not appear to be more serious than it was when he first hurt his right hamstring late in the first half of the season opener.

Marrone said Fournette feels a "catch" in the hamstring when he tries to accelerate to top speed.

"There's a thing that's just pulling at it," Marrone said. "It's legit. There is something there, and we've just got to do everything we can to get that out. That whatever thing is that feels like it catches. That's all I know.

"I don't know all the doctor talk about it. I'm just trying to give you the layman's talk. It's just, 'Hey, I just got this little thing. It feels like it catches. It doesn't enable me to open up.'"

Fournette ran 11 times for 30 yards and caught one pass for 5 yards before going to the bench late in the first half against the Jets. The team originally said he was questionable to return, but he went back onto the field for the Jaguars' final drive. The team ruled him out for the second half.

Fournette missed the Jaguars' games against New England and Tennessee, and based on what Marrone said Monday it's unlikely Fournette plays on Sunday in Kansas City. The Jaguars (3-1) play at Dallas the following week before playing host to Houston and then traveling to London for the team's annual home game in Wembley Stadium.

The Jaguars have their bye the following week, so it's not out of the question that Fournette could be held out until their Week 10 game at Indianapolis on Nov. 11.