The 25-year-old missed his first game since coming into the side in August on Saturday as he was ruled out of the 3-1 win over Cambridge with illness.
Boss Paul Warne was hopeful that he could travel with the squad to Suffolk on Monday night ahead of Tuesday’s trip to Portman Road.
The return of Rathbone, who has been one of the star performers in the Millers side this season, would be an obvious boost.
"He's an option for us to travel," Warne said. "I still haven't made a call on it. I'm going to see how he is today. We haven't trained yet.
"Obviously, if I can take him and use him I will. As I speak to you now, I don't honestly know yet if he will be in the squad, but I'd like to think he will play a part."
The Millers expect to have Will Grigg, who suffered a foot injury on Saturday, with a scan showing there was no fracture.
Boss Warne does at least have in-form striker Michael Smith at his disposal after he served a one-match suspension against the U’s..
"Griggy had a little bit of a sore foot after Cambridge," Warne added. "He had a scan on that and it's come back negative.
"There are no issues. It was just about ruling out a fracture. There is no fracture and he hasn't got severe pain today. We should have virtually every pro available."
The Millers go to Portman Road in second position in League One and on a 14-game unbeaten run in all competitions.
They have swatted some promotion rivals aside on that run, but the test against Ipswich will be a stern one, with Paul Cook’s side coming good after a sticky start.
Warne added: "I've always liked Cooky and the way his teams play. He's nearly always 4-2-3-1.
"He had a bit of a sticky start. A new team took time to gel. I think they are gelling now and I wish I'd played them a few weeks ago. I'm expecting a really hard game. They create chances and keep the ball really well.
"It's a game we want to go and try to win so we'll pick an aggressive side. I still think that if you finish above Ipswich you will take one of the automatic spots."