Liriano (7-3) held Milwaukee to one run on seven hits and a walk while striking out six in notching his fourth victory in five starts.
Tony Watson and Mark Melancon each supplied a scoreless inning of relief and Jason Grilli racked up his 27th save with a 1-2-3 ninth for National League Central-leading Pittsburgh, which became the first team to win 50 games this season (50-30).
Brewers starter Donovan Hand (0-1) was saddled with his first major-league loss, surrendering two runs on five hits over five frames.
Yuniesky Betancourt drove in Milwaukee's only run.
Notable deaths of 2014 [PHOTOS]