"I will talk to Manuel tomorrow. We let the Austrians get back in the game".
Loew last coached at club level in 2004, when he was at Austrian Vienna, and under his stewardship Germany has reached at least the semi-finals of every worldwide tournament since the 2006 World Cup.
Four other World Cup finalists failed to score between them as European champions Portugal drew 0-0 in Belgium and the Scandinavian derby between Sweden and Denmark also ended goalless.
But Martin Hinteregger equalised with a superb angled volley before Alessandro Schopf steered in the victor.
Siebenhandl made amends by keeping out Ozil's tamer 16th-minute effort before getting his fingertips to Julian Brandt's unsafe effort four minutes later.
"In two weeks, the team will be very differently prepared and I won't be having sleepless nights". Today many things were bad.
At the other end, Neuer made his first save on 16 minutes to deny attacking midfielder Schoepf.
After 259 days out injured, Neuer pulled off a string of saves in an impressive first-half display, but had little chance to stop Austria's goals after Germany's defence leaked badly in the second half.
Germany's Mesut Ozil, left, vies for the ball with Austria's David Alaba during a friendly soccer match between Austria and Germany in Klagenfurt, Austria, Saturday, June 2, 2018. And the second thing was that he reacted great in many situations, he reacted fast.