Martinez (10-3) scattered four hits while striking out five and walking three in improving to 7-1 with a 1.20 ERA in his last 10 starts.
The right-hander is one of the five players contending for the NL’s All-Star Final Vote. Fan voting ends Friday afternoon and the game will be played Tuesday at Cincinnati.
St. Louis (56-31) opened a 5 1/2-game lead on the Pirates in the NL Central. Pittsburgh (50-35) had its five-game winning streak snapped in the opener of a four-game series.