It is Opening Day in the National League. At West Side Park in Cincinnati, the Chicago Colts spoil the official opening of the new park by beating the Reds, 4 – 3, with two runs in the bottom of the 9th inning. This is the first professional game ended in “sudden death,” as the old rules required that the full inning be played out even if the team batting last was already ahead.

This Day In Baseball

On May 1, 1890 — It is Opening Day in the National League. At West Side Park in Cincinnati, the Chicago Colts spoil the official opening of the new park by beating the Reds, 4 – 3, with two runs in the bottom of the 9th inning. This is the first professional game ended in “sudden death,” as the old rules required that the full inning be played out even if the team batting last was already ahead.

Source
Baseball Reference May 1