The Scot has missed the last three games with a groin problem, which came after he scored and got an assist in a 2-1 win at Blackpool.
The Millers could have done with his threat from set-pieces as they laboured to a 1-0 loss to Wycombe at the weekend.
But Warne, who expects his defender to be back in training this week, will not hit the panic button and throw Robertson into the side at Gillingham on Saturday unless he is ready.
“I’m hopeful of him returning to training this week,” Warne said. “He is in less pain but I have got to make sure he is right before he comes back in, I am not going to have a knee-jerk reaction just because we have lost and be in a massive panic get him back.
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“I will be directed by the physios. I am hopeful but I don’t honestly know.”
Warne could have Shaun MacDonald back after illness while Richard Wood should also be fit after coming off with a knock against the Chairboys.
“He is ill, unfortunately, so he didn’t make the squad,” Warne added of MacDonald. I can’t say what it is. It is a bit personal, to be fair.
“Woody looked like he broken his hooter. He looked a bit battered and bruised. But I don’t think there are any injuries.”
There were few bright points for the Millers at the weekend, though the performance of Chiedozie Ogbene was perhaps one of them.
The flying winger was making his first start for the club after sustaining a hamstring injury as a substitute on debut and showed glimpses of what he can bring.
“Physically, I felt I could handle it,” he said. “I was really happy to be out there, running about and getting my fitness up. I need to improve on other stuff to help the team as best as I can.
“I’m really disappointed for the guys. They’re a great bunch of lads. I see the work they and the manager put in.
“For us to not show up and deliver our best is sad to see.
“There weren’t enough good individual performances to get us over the line. I feel that we need to be a bit braver, especially at home.”