ST. LOUIS -- Milwaukee Brewers opener Matt Bush exited after recording just one out against the St. Louis Cardinals because of right groin discomfort Tuesday night.

Bush, who was starting a bullpen game for the Brewers with three starters already on the injured list, made just 15 pitches before leaving.

Bush had walked Brendan Donovan, allowed a single to Tommy Edman and got Paul Goldschmidt to ground out. He left after making the first pitch to Nolan Arenado. Peter Strzelecki came on in relief to finish the inning.

The Brewers are playing the first of two against the Cardinals. St. Louis led Milwaukee by eight games in the NL Central.