Marcell Ozuna hit a grand slam during a six-run first inning, Miles Mikolas pitched six strong innings and the St. Louis Cardinals beat the Chicago Cubs 6-2 Saturday in front of a season-high crowd of 47,514 at Busch Stadium.

The Cardinals improved to 9-6 this season against the NL Central-leading Cubs. Chicago has lost four of six overall.

Ozuna hit his second grand slam this season and the fifth of his career. Ozuna had three hits.

Jose Martinez drew a bases-loaded walk from Jose Quintana (9-7) and Ozuna followed with his 11th home run. Yairo Munoz added an RBI double.

The last time the Cardinals scored six runs in the opening inning was eight years to the day, on July 28, 2010, against the Mets.

Quintana needed 33 pitches to record his first out and 51 pitches to get through the first. The six runs were the most Quintana has allowed in the first inning this season — he had given up just four earned runs in the first inning through 19 starts this year.

Mikolas (11-3) allowed six hits, including a two-run homer by Javier Baez, who connected for the second time in the series. Three St. Louis relievers each pitched a scoreless inning.