With light rain falling during the final laps the WorldSBK riders had to focus hard in order to avoid any mistakes and Davies did just that to register a third victory in four races at Lausitzring. Coming from the back of the third row on the grid the Welshman ultimately beat Rea across the line by 2.29s, with Melandri just over two further seconds back having held the lead early in the race.
Despite setting pole on Saturday Tom Sykes (Kawasaki Racing Team) could not stay with the front three on this occasion and finished in fourth place having started Race 2 in seventh on the grid.
The results saw World Champion and standings leader Rea open up a 70-point gap over his teammate Sykes in the standings with four rounds to go.
Alex Lowes (Pata Yamaha Official WorldSBK Team) just beat Leon Camier (MV Agusta Reparto Corse) to fifth by 0.237s, with five Britons finishing in the top six.
Just behind them on the finish line was Lorenzo Savadori (Milwaukee Aprilia) as the top Aprilia-equipped rider, just trailing Camier by 0.115s in that tight group also involving Lowes.
Jordi Torres (Althea BMW Racing Team), German wildcard Markus Reiterberger (Van Zon Remeha BMW) and Xavi Fores (BARNI Racing Team) completed the top ten. A brave ride by Stefan Bradl (Red Bull Honda World Superbike Team) saw him finish 13th, after he missed Race 1 due to severe elbow pain from a crash on Friday.
Randy Krummenacher (Kawasaki Puccetti Racing), Eugene Laverty (Milwaukee Aprilia) and Pawel Szkopek (Pazera Racing) all crashed out, with Riccardo Russo (Pedercini Racing SC-Project) also suffering a DNF as a late retiree.
The WorldSBK grid return to action in just under a month (15th-17th September) at the Autodromo Internacional do Algarve, Portimão, Portugal.
1st - Chaz Davies (Aruba.it Racing - Ducati)
"It's incredible, I knew the second race was going to be tighter, it was hard to come from the third row, I made some good passe out there and had a lot of fun. It was a a case of setting my won rhythm, we had a lot of fast sections but they were quicker than me in other sections and for that reason it was harder to get away, but I made some good passes and got the job done."
2nd - Jonathan Rea (Kawasaki Racing Team)
"It was as much as we could expect, I really emptied the tank in that race, the bike is so easy to ride here so I gave it 100% to bring the fight to Chaz. I did all I could to stay with him but he was so fast and I was beaten by a better guy today and we look forward to the next one."
3rd - Marco Melandri (Aruba.it Racing - Ducati)
"After yesterday I couldnt beleive to inish on the podum today but the team amde an asesome job, a fwe orenrs it was too slow, i couldnt open the throttle too mich but I am happy ith the result and thanks to all the guys."
#GermanWorldSBK at Lausitzring: Race 2
1. Chaz Davies Ducati
2. Jonathan Rea Kawasaki +2.290
3. Marco Melandri Kawasaki +4.388