JACKSONVILLE -- This task has an urgent feel.

And when it comes to addressing the Jaguars' struggling run defense while preparing to play an offense that rarely struggles to run, Head Coach Doug Marrone on Wednesday put it simply.

"We've got to do a better job; there's no doubt about it," Marrone said as the Jaguars (2-2) prepared to play the Pittsburgh Steelers (3-1) at Heinz Field in Pittsburgh Sunday at 1 p.m.

The Jaguars, who through four games rank 11th in the NFL in total defense and first against the pass, enter Sunday last in the NFL against the run. They allowed touchdown runs of 75 and 69 yards – and 256 yards rushing overall – in a loss to the Jets Sunday.

Marrone on Wednesday was asked if he was surprised with the run defense.

"Surprised?" he said. "Yeah, because if I wasn't surprised then I should have fixed that problem a long time ago."

Steelers running back Le'Veon Bell, a two-time Pro Bowl selection, rushed for a season-high 144 yards and two touchdowns in a victory at Baltimore Sunday. Bell rushed for 1,361 yards in 2014 and 1,268 last season, rushing for 556 in six games in 2015.

"It will be a challenge," Marrone said of Bell.

Marrone said after the Jets loss a major issue was defenders in the Jaguars' gap-control defense being out of gaps. That often leads to long, gashing runs against that scheme, and it happened on multiple occasions Sunday.

"It's easy to point the finger at the first level [defensive line], which is, 'Hey, we should be in that gap,''' Marrone said. "Then, you get to the second level: 'Hey, who's going to cover our butt?' Then, you get to the final level, which is who's going to cover it.'

"Specifically, was there a breakdown at the first level? Yes. It's always the case like that in the run game with fits, then it's second level 'bail us out' and third level: 'Let's get the guy down and play another down.'''

Also Wednesday morning:

*Marrone as he did Monday discussed rookie running back Leonard Fournette's workload. Fournette rushed 24 times and caught four passes against the Jets and has 285 yards with three touchdowns on 81 carries this season. His carries are second to Bell in the AFC and Marrone said he wasn't concerned with Fournette having too many carries. "We just have to keep pushing it and see where it is," Marrone said. "He's responded to everything we've asked him to do. We just have to do a good job of managing ourselves where you want the players on the field in certain situations. I think I can do a better job of that and put him out there." …

Marrone said a major focus this week will be third-down offense. The Jaguars' 83 first downs are 11th in the NFL, but they have converted 16 of 52 third downs – 30.8 percent. That's 29th in the NFL and ahead of only Cleveland, Miami and San Francisco. "The irony of it is on third-and-7-to-10, we're above the league average: 44 percent," Marrone said. "Which is really, really good. But [on third-and] one-to-six – and specifically on-to-two – we're at half the league average. That's the thing that really gets you. You fight so hard to put yourself in good down and distances so you can open up more of the playbook and we haven't converted on that. That's where I think the issue is and it's one of the things we're focused on this week."

*Marrone discussed a Steelers defense that ranks second in the NFL and second against the pass. They rank second in the NFL with 15 sacks, which is three behind the Jaguars' league-leading 18 sacks. "The production remains the same, the names just change, it seems," Marrone said.

*Three Jaguars players are not expected to practice Wednesday: wide receiver Marqise Lee (ribs), safety Jarrod Wilson (shoulder) and center Brandon Linder (illness). Nine other players expected to practice appeared on the injury report: quarterback Blake Bortles (right wrist), wide receiver Jaelen Strong (hamstring), cornerback Jalen Ramsey (ankle), Fournette (ankle), fullback Tommy Bohanon (knee), linebacker Donald Payne (hamstring), linebacker Lerentee McCray (knee), guard A.J. Cann (hand) and defensive tackle Malik Jackson (groin). …