Pirates 6, Cardinals 0: Andrew McCutchen hit a two-run homer and fill-in starter Brandon Cumpton tossed seven superb innings for his first career victory as host Pittsburgh completed a doubleheader sweep of sinking St. Louis.

Cumpton (1-1) allowed three hits and a walk while striking out five after being recalled to serve as the 26th man and make the start. The Pirates won the opener 2-1 on Alex Presley’s 11th-inning single and have the best record in the major leagues at 64-42.

Jordy Mercer, Gaby Sanchez and Tony Sanchez also had RBIs as Pittsburgh took a 1 1/2-game lead over the Cardinals in the National League Central. St. Louis has lost a season-worst six straight games, scoring just five runs during the skid.

Mercer’s bloop single in the fifth gave Pittsburgh a 2-0 lead and McCutchen followed with his 15th homer, a blast to left field that caromed off Matt Holliday's glove and over the fence. Gaby Sanchez had a run-scoring double in the seventh and Tony Sanchez added a sacrifice fly later in the frame to help the Pirates improve to 3-0 in the five-game series that concludes Thursday.

Tyler Lyons (2-4) was recalled to start for St. Louis and gave up four runs (three earned) and eight hits in six innings.

GAME NOTEBOOK: Cardinals C Yadier Molina left after three innings with a sprained knee and is likely to land on the disabled list. … Pittsburgh had three triples – one apiece by Starling Marte, Josh Harrison and Presley. … St. Louis acquired minor-league INF Juan Herrera from the Cleveland Indians for LHP Marc Rzepczynski.