Hours before the crucial qualifier on Tuesday night, midfielder Kroos wrote on Twitter:
Although the Real Madrid player thought tonight's opposition was Scotland, he was at least right in recognizing the importance of the game with his hashtag "wichtig".
He later wrote on Twitter: "The astute ones among you have noticed... the game is of course against Ireland. Nevertheless, important."
World Champions Germany lost to Poland on Saturday and are now third in the their qualification group.
In a blow to their chances against Ireland, Schürrle was ruled out with flu hours before kick-off, leaving Julian Draxler or Lukas Podolski to take over on the left wing.
Schürrle's absence leaves coach Joachim Löw with few options. He has already lost Bastian Schweinsteiger, Sami Khedira, Mesut Özil, Benedikt Höwedes, Marco Reus and Mario Gomez to injury.
Draxler said the world champions see it as their “duty” to beat Ireland on Tuesday night to get their Euro 2016 qualification campaign back on track.
Just three months after lifting their fourth World Cup title, Germany host the Irish in Gelsenkirchen desperate for a win after Saturday's 2-0 defeat to Poland in Warsaw.
The result in Warsaw left the Germans third on three points alongside Scotland in Group D with Ireland second to Poland on goal difference, and both teams with six points from two matches.
Ireland crushed minnows Gibraltar 7-0 in Dublin on Saturday after captain Robbie Keane scored a hat-trick inside 12 minutes.
Martin O'Neill's Ireland are chasing their first win over Germany in 20 years, but Draxler said there is a determined air in the German squad to make amends after Warsaw
"The 2-0 defeat hurt. We see it as our duty to get the rudder back on course," said the 21-year-old Draxler. "Being world champions doesn't mean being unbeatable."
And as Germany's goalkeeper and stand-in captain Manuel Neuer put it: "Everyone wants to beat the world champions".
Injuries and retirements have robbed coach Joachim Löw of experience in key positions since Brazil.
The flow of goals has dropped since record goalscorer Miroslav Klose hung up his boots after the World Cup and the calming influence of retired defenders Philipp Lahm and Per Mertesacker is also missing.