Key strikers Pierre-Michel Lasogga and Ivica Olic, plus midfielder Petr Jiracek, will be given every opportunity to prove their fitness before Hamburg's promotion-relegation play-off first leg.
Hamburg coach Bruno Labbadia confirmed "two or three players are still uncertain" ahead of Thursday's first leg against Karlsruher, with Lasogga (shoulder), Olic (back) and Jiracek (knee) struggling with injuries.
Lasogga hurt his shoulder during Hamburg's 2-0 win over Schalke on Saturday, ensuring Labbadia's side would avoid automatic relegation from the Bundesliga.
Olic played 88 minutes, scoring Hamburg's first goal, before he was replaced by Jiracek.
"I can't say for sure which line-up we're going to have on Thursday," Labbadia said on Tuesday.
"Obviously, I've got something in my mind but two or three players are still uncertain for the match, so nobody is ruled out."
Hamburg avoided relegation via the play-off last year after an away-goals victory over Greuther Furth, and Labbadia underlined the importance of keeping a clean sheet at Imtech Arena.
"It's always good not to concede at home, because that makes it difficult for the opponent, since they know it will be double-trouble if we score an away goal," the 49-year-old coach said.
"We know that from the past, so it would be good to keep a clean sheet and to win the match."
Hamburg are the only club to have played in every season in the Bundesliga's history.
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