Eto'o, 33, said on Monday he had virtually no hope of appearing in the game, with Cameroon needing at least a point to avoid a group stage exit. (Agencies)
The Indomitable Lions lost their opener 1-0 against Mexico, when Eto'o came on as a substitute but felt a recurrence of a niggling knee injury he has been battling for the last few months.
"I think the most important thing for us is that Samuel is with us, perhaps as a substitute," Finke told a news conference on Tuesday.
"I think it would be very very hard for him to start because we're dealing with health matters here and we can't work miracles," he said.
Eto'o, who has scored 54 goals for Cameroon, said he had not had the time needed over the last few months to fully recover.
"Even if I knew I'd be playing or not I wouldn't say anything ... we can't reveal our strengths and weaknesses to our opponents," he said.
Cameroon did not perform particularly well against Mexico and were disheartened by the loss, Finke said.
"Our spirits were low, that's normal, because a defeat like that hurts. We didn't play well in the first half, we were a little bit better in the second half but we missed some chances ... but I think the players can hope for improvement," he said.
Even though Mexico and Brazil already have four points, Finke said qualification was still a possibility for Cameroon and Croatia if they drew on Wednesday.
"No one can sleep because everything remains open ... if the match is a draw, the last games will be really crazy," he said.
Eto'o, 33, said on Monday he had virtually no hope of appearing in the game, with Cameroon needing at least a point to avoid a group stage exit.