The Shrimps travel to the New York Stadium to meet a Millers side six points clear at the top of the table.
O’Carroll said: “I’m a big fan of what they do. When they came here earlier in the season, they pressed us and they were well organised.
“I remember thinking afterwards that they were a good side and they were well coached.
“The intensity of what they do is their main strength, we know they put teams under constant pressure and they will press the life out of you – but we do try and play through people.
“They have some very good players but they are, perhaps, a collective rather than a team of individual stars but it’s going to be very difficult.”
The scale of the task facing Morecambe tonight can be seen by the respective home and away form tables for League One.
Rotherham are the division’s best team on home soil with 36 points from 16 games.
In contrast, the Shrimps boast the second worst record away from home with nine points from 45 on their travels.
Nevertheless, O’Carroll believes they can take heart from some of their performances against the sides at the top end of the table.
“We’ll back ourselves because we’ve done well against the better teams,” he said.
“We have a plan to try and hit them in certain ways. If we can start on the front foot then all of the pressure is on them.
“People think we’re going to go there and get thumped. It’s going to be a challenge but every game is like that.”
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