Tottenham face PAOK Salonika, who finished fourth in the Greek Super League last season, on Thursday before a key Premier League clash with Liverpool at the weekend.
Redknapp already said his Europa League selections would be based around how important the following league game is.
William Gallas, Michael Dawson, Vedran Corluka, Steven Pienaar, Rafael van der Vaart, Tom Huddlestone and Aaron Lennon all missed Saturday's game against Wolves, leaving the Spurs boss to pick from the bones of his squad.
"The whole situation is a nightmare," said Redknapp. "I have no idea what team I will be able to play.
"I will sit down on Tuesday and see who I can take out to Greece. It may well be a chance for some of the fringe players to take their chance.
"I really don't know who will be ready for Liverpool."