Jack Flaherty pitched five effective innings for St. Louis in his first big league action since June, but the bullpen let him down as the Cardinals had their four-game winning streak stopped by Joey Meneses and the Washington Nationals 6-0 Monday.
Meneses got three hits and fellow rookie C.J. Abrams had four to back five shutout innings from Aníbal Sánchez (2-5). Washington, which has the worst record in the majors, has won three in a row.
Flaherty (0-1) returned from the injured list after being sidelined by a right shoulder issue. In his first start since June 26, he allowed one run on six hits and a walk. He struck out six and hit a batter while throwing 91 pitches.
St. Louis managed just three singles against three pitchers.
The Cardinals optioned RHP Dakota Hudson to Triple-A Memphis and designated RHP Junior Fernández for assignment. Fernández appeared in 13 games in relief for the Cardinals this season with a 0-0 record and a 2.93 ERA.
LHP Steven Matz (left MCL tear) will begin a minor league rehab stint Tuesday with Double-A Springfield. When he returns later this month, the Cardinals plan to use Matz out of the bullpen.
LHP José Quintana (4-6, 3.47) will be making his third start of the season against the Nationals and his first as a member of the Cardinals, 5:50 with the pregame and the first pitch at 6:45 on KIRX.
The Brewers beat the Rockies 6-4, so the Cardinals lead is 7 ½ games.