Liriano narrowly escaped damage in the third Sunday when Matt Holliday lined to right with the bases loaded.
The left-hander wasn't quite as fortunate in the fifth. Jon Jay led off with a single and Pete Kozma followed with a walk. After pitcher Joe Kelly struck out trying to bunt, a double steal set up Beltran's two-run single.
At 2-all, the Cardinals had matched their entire output against Liriano in their previous 28 innings.
Liriano was matched nearly pitch for pitch by the unflappable Kelly. The 25-year-old right-hander has been rock-steady all season, even as he moved from middle reliever to starter in July.
Kelly welcomed the hostile environment, calling the sea of black-clad fans that awaited him one of the things a kid dreams about.
The reality proved a little more unnerving, at least when Byrd hit a two-run single in the first.
The well-traveled outfielder — who played in 1,250 regular-season games before reaching the playoffs for the first time — has been a welcome jolt both in the lineup and in the clubhouse for the Pirates.
"Just having a heck of a time," Byrd said.
NOTES: Grilli worked around a leadoff single in the ninth. ... McCutchen is batting .538 (7 for 13) and has an on-base percentage of .684 in the playoffs. His five walks rank first in the league this postseason. ... Beltran's home run was the first by the Cardinals in 10 games at PNC Park this year.