Petrina, an accomplished singer, belted out the national anthem prior to the National League Central-leading Bucs' game.
During the game, Andrew belted his 16th homer and later added a single as the Pirates improved their division lead over the St. Louis Cardinals to three games.
As Petrina's powerful voice carried over the ballpark, a cappella, Andrew was lined up along the third-base dugout along with his teammates.
After his mom finished, and before he took the field, Andrew greeted her with a warm hug.
"It's always great to watch her go out and perform," he said. "Every day is always new, and it's always great to be able to hear her just show her gift."
"Singing is what I do. I'm not a novice at it," Petrina said. "I enjoy it. Just the fact that it's here in Pittsburgh, to see my son play and to get this opportunity, it's a once-in-a-lifetime opportunity, and I'm glad they invited me."
In truth, it became a twice-in-a-lifetime opportunity when the Pirates invited her to do an encore performance, on the first anniversary of her PNC Park debut. Petrina also rendered the anthem during the Pirates' series with the D-backs early last August.
"They asked me back. It came to fruition," she said. "I think someone had heard me sing and mentioned it to [team president] Frank Coonelly. One thing led to another and I got invited. I think my audition was down in Bradenton, [Fla., the Pirates' Spring Training home] to see if I really could sing, and it kind of took off from there. I'm fortunate they liked what they heard and invited me back."
Considering how the mother-and-son performance went, and baseball's culture of superstition, it would not be surprising if Petrina returns yet again to perform the anthem at PNC Park. Prior to the Pirates' first postseason game in 21 years, perhaps?