The German international played for the club's U23s on Monday night in his first appearance since April.
The Blues are winless in three straight games but Rudiger thinks it would be wiser to take his time returning to the first-team.
"I've been back for almost two weeks with the team and I'm feeling better each day but of course there is still game fitness missing, which is what I need to get better," the 26-year-old told the official Chelsea website.
"I know I need to be patient. There's no need to rush anything at the moment because we have a long season to go.
"You have to go day by day and that is what I'm doing."