Pedro Alvarez hit a grand slam in the first inning off 10-game winner Lance Lynn and Andrew McCutchen had two hits as the Pirates beat the 7-3 Saturday for their fourth victory in a row and second over the Cardinals.
Pittsburgh starter Jeff Karstens (1-2) allowed four hits with seven strikeouts in seven innings for his first victory since Aug. 10, 2011 at San Francisco.
Pittsburgh matched its longest winning streak of the year aided by fast starts with 11 first-inning runs the last three games, and stayed one game back of NL Central-leading Cincinnati. It was 99 degrees for the first pitch and the temperature spiked to 103 later in the game.