Mattias Ekstrom set the pace in DTM free practice at the Norisring, as Audi locked up the top four spots.
The Ingolstadt-based manufacturer is attempting to win on the German street circuit for the first time since Laurent Aiello's dramatic victory in 2002. It carried out an extensive simulation of the short track on a German airfield recently, as it did last year, and the signs so far suggest that it will give Mercedes a hard time as it did in 2009.
Ekstrom's final lap of the session was his best effort, leaving him just under 0.1sec ahead of reigning champion Timo Scheider. Martin Tomczyk was third in another 2009-spec Audi, while Alexandre Premat was the top driver in a 2008 car in fourth place.
Maro Engel was the highest-placed Mercedes runner by the end of the session. Things had looked good for the 2008-spec Mercedes drivers for most of the session, as Jamie Green and David Coulthard set the pace for a long time.
Both slid down the order as other drivers improved. Green ended up eighth behind Mike Rockenfeller and Ralf Schumacher, while Bruno Spengler bumped Coulthard down to 10th place.
Just seven tenths of a second covered the whole field at the end of the 90-minute session, and the closeness of all 18 cars meant that there were some surprising names in the bottom half of the times.
While his Abt Sportsline teammates occupied the top three, Oliver Jarvis ended up 13th in the fourth 2009-spec Audi. Directly behind him were fellow Britons Gary Paffett and Paul di Resta in their HWA Mercedes.