Tsutsugo’s blast, which cleared the right field stands but did not reach the Allegheny River, enabled the Bucs to split their four-game set with the Cardinals.
The Pirates trailed 3-1 heading into the ninth inning with Alex Reyes on in search of his 30th save of the season for St. Louis.
Bryan Reynolds drew a walk and after Colin Moran struck out on a high fastball, Jacob Stallings walked, moving Reynolds to second.
That brought up Tsutsugo, who wasted no time in delivering his walk-off blast. It was Tsutsugo’s fifth homer of the season.
The Pirates got fine work from their bullpen, as Chad Kuhl, Will Bednar and Chris Stratton combined to blank the Cardinals on one hit over the final four innings.
The Cardinals opened the scoring in the third off Pirates starter Wil Crowe when Tommy Edman doubled with one out and came around to score on Tyler O’Neill’s two-out triple.
The Pirates tied it with a run in their half of the fourth. Three consecutive singles by Ke’Bryan Hayes, Reynolds and Moran loaded the bases off Cardinals starter Kwang Hyun Kim. After Stallings struck out, Tsutsugo delivered a sacrifice fly to score Hayes, but Cole Tucker stranded a pair of runners when he grounded into a force out.
St. Louis took the lead in the top of the fifth when Matt Carpenter walked to lead off the inning and Edman smacked a two-run homer to make it 3-1.
Crowe worked the first five innings, giving up five hits and all three runs while walking three and striking out four.
NOTES – Nick Gonzales, the Pirates’ top draft pick in 2020, crushed three home runs – including a grand slam – and drove in eight for High-A Greensboro Sunday. Gonzales finished 4 for 7 on the day and now has 14 home runs on the season. Double play mate Liover Peguero added two hits, including his 14th homer of the year.