Paul di Resta put in a late charge to top the second DTM free practice session at Brands Hatch.
The Scot, who won the race here last season, went to the top of the time sheets in the closing stages as Mercedes finally showed its hand against Audi for the first time this weekend.
Audis had set the pace for most of the session, with Mattias Ekstrom and Timo Scheider taking turns at the top.
But di Resta's effort blew Scheider's away by nearly three tenths of a second. Oliver Jarvis then responded for Audi by getting within one tenth of the Scot's pace, good enough for second position.
Mercedes' Gary Paffett put a lap in at the end of the session to complete a British 1-2-3, bumping reigning champion Scheider to fourth.
Championship leader Bruno Spengler completed the top five, while Ekstrom eventually had to settle for sixth.
Ralf Schumacher had gotten himself as high as second with just a few minutes remaining. But the German opted to sit out the final few moments of the session, so he was unable to respond as others dropped him back to seventh.
Martin Tomczyk had a difficult session in the fourth Abt Sportsline Audi but eventually managed to set the eighth fastest time, while the 2008-spec cars of Jamie Green and Alexandre Premat completed the top 10.
Pos Driver Car Time Gap
1. Paul di Resta Mercedes 41.101s
2. Oliver Jarvis Audi 41.166s + 0.065s
3. Gary Paffett Mercedes 41.313s + 0.212s
4. Timo Scheider Audi 41.388s + 0.287s
5. Bruno Spengler Mercedes 41.396s + 0.295s
6. Mattias Ekstrom Audi 41.413s + 0.312s
7. Ralf Schumacher Mercedes 41.414s + 0.313s
8. Martin Tomczyk Audi 41.548s + 0.447s
9. Jamie Green Mercedes 41.600s + 0.499s
10. Alexandre Premat Audi 41.611s + 0.510s
11. Maro Engel Mercedes 41.647s + 0.546s
12. Miguel Molina Audi 41.710s + 0.609s
13. Mike Rockenfeller Audi 41.765s + 0.664s
14. Susie Stoddart Mercedes 41.820s + 0.719s
15. Markus Winkelhock Audi 41.881s + 0.780s
16. Cong Fu Cheng Mercedes 41.937s + 0.836s
17. David Coulthard Mercedes 41.959s + 0.858s
18. Katherine Legge Audi 41.996s + 0.895s