Mariners starters have not allowed a run in this series, which concludes Sunday with Erasmo Ramirez getting the ball for Seattle at Busch Stadium.
St. Louis (86-62), tied with Pittsburgh for the NL Central lead, has managed five hits in 13 innings against Seattle's starters in splitting the first two games. Hisashi Iwakuma lasted seven innings in the Mariners' 2-1, 10-inning loss Friday before rookie James Paxton pitched six innings to record Saturday's 4-1 victory.
"There's nothing wrong with us getting a couple of hits early,'' said Cardinals manager Mike Matheny, who has watched his club average 3.0 runs while batting .164 over its last five games. "There's nothing wrong with getting a couple of runs."
The Cardinals had never seen those pitchers before and face the same situation Sunday against Ramirez (5-1, 4.57 ERA), who is 3-0 with a 4.15 ERA in five road starts.
"We've faced the Pirates 100 times and we know exactly what A.J. Burnett has, we know what Francisco Liriano has, and those kinds of guys," St. Louis second baseman Matt Carpenter said. "Then we come in here and we've got these guys, and nobody knows anything about anybody."
Ramirez is making his first 2013 interleague start after going 0-1 with a 9.00 ERA in two outings last year as a rookie. The right-hander enters after throwing six-plus scoreless innings last Sunday in a 4-1 home defeat to Tampa Bay.
"I thought Erasmo was good," manager Eric Wedge said. "I loved his aggressiveness early in the game and he was able to hang on to it and sustain it."
Although the Cardinals are battling for the playoffs and the Mariners (66-82) will miss the postseason for the 12th straight year, a victory by Seattle on Sunday would give both teams 9-11 interleague marks.
Numerous St. Louis hitters are scuffling. Yadier Molina is hitless in 15 at-bats as part of a 6-for-47 slump, David Freese had two hits in 16 at-bats, Carlos Beltran is in a 3-for-21 slide and Jon Jay a 1-for-13 skid.
Carpenter has carried the offense by reaching base in 14 straight games, batting .370 with 15 runs scored in that span.
Kendrys Morales homered for the fifth time in 10 games Saturday as Seattle ended a five-game slide. Morales is 6 for 11 in his last three, including 4 for 8 in this series.
None of Seattle's hitters has faced the Cardinals' Shelby Miller (13-9, 3.05), who enters off a scoreless effort like Ramirez. Miller pitched 6 2-3 innings to earn Tuesday's 4-2 win over Milwaukee, improving to 8-3 with a 1.76 ERA in 14 home starts.
The right-hander is bidding to become the first St. Louis rookie to win 14 games since Dick Hughes won 16 for the 1967 World Series champions. Miller is 1-2 with a 6.87 ERA in four interleague starts.
Seattle leadoff hitter Brad Miller was removed Saturday with a mild left hamstring strain after running out a sacrifice bunt in the fifth. He is day to day.