"This is 20 years of waiting. You're seeing it all come out in one night," Martin said. "Hopefully we can keep this atmosphere till late October."
Cincinnati starter Johnny Cueto gave up four runs in 3 1-3 innings and appeared rattled by a raucous ballpark that taunted him throughout by chanting his name.
The 36-year-old Byrd, acquired by the Pirates in late August from the New York Mets, celebrated the first postseason of his 12-year career 1,250 games by sending Cueto's fastball into the seats to give the Pirates the lead in the second inning.
Martin then sent a drive into the bleachers in left field to make it 2-0. The Reds never recovered, ending a 90-win season with a six-game losing streak.
Liriano was signed on the cheap in the offseason after a mediocre 2012 season with the Minnesota Twins and the Chicago White Sox. He has been reborn in Pittsburgh, going 16-8 with a 3.02 ERA during the regular season, his devastating slider nearly unhittable against left-handers.
The Reds proved no match. Joey Votto went 0 for 4 with two strikeouts, and Jay Bruce managed just one RBI single in the fourth.
It was Pittsburgh's first postseason game since Atlanta's Sid Bream slid into home ahead of Barry Bonds' throw in the bottom of the ninth in Game 7 of the 1992 National League championship series.
The victory sent the Braves to the World Series and the Pirates into an abyss it took an entire generation to escape.
The first step came with victory No. 82 on Sept. 9. The next came two weeks later when a win over the Chicago Cubs assured a wild-card spot.
The most thrilling win yet lifted the team with the 26th-highest payroll in Major League Baseball ($73.6 million) into a showdown with the Cardinals in the NL division series.
