The 29-year-old has been sidelined with a hamstring injury sustained against Atalanta at the start of November.
And Varane has explained why he is not rushing back too soon.
"Yes, I'm working very hard and, you know, footballers are like F1 [cars] so sometimes we have to change something and to improve the motor," he told club media at Carrington.
"I think I have to change a little thing because it's a big difference, a big change.
"The kind of work is different work so I have to adapt. I know that and I'm working very hard to be at my best as quickly as possible. I know it's big work but I'm ready to do it, to try to improve.
"I'm very excited to come back to help the team."