Ethier and Ryan Theriot each hit solo shots in the second inning for a 3-0 Dodgers lead, and Jay Gibbons and Matt Kemp went long back-to-back in the next frame to power Los Angeles.
Casey Blake drove in two runs and scored twice for the Dodgers, who squared their three-game series with the Reds at one win apiece.
Chad Billingsley (10-7) yielded three runs on seven hits over 5 2/3 innings to collect the victory. Jonathan Broxton notched his 22nd save of the season.
Johnny Cueto (11-4) was saddled with the loss for the Reds, who saw their seven-game winning streak snapped.
Joey Votto drove in a pair of runs for Cincinnati.
Copyright 2010 United Press International, Inc. (UPI).