When St. Louis and Pittsburgh opened a series last weekend, the Cardinals were in third place in the National League Central, the Pirates in second.
As the teams launch into a four-game series Thursday, this time switching venues to Busch Stadium, things have changed. St. Louis (29-24) has dropped to third, Pittsburgh (29-26) to fourth.
Neither club has taken great advantage of a stretch of games against other contenders in the division.
The Cardinals took two of three in Pittsburgh, but then dropped two of three at first-place Milwaukee, including a 3-2 loss Wednesday when they blew a one-run lead in the seventh.
"We had a momentum shift, and then we had to change gears," St. Louis manager Mike Matheny said. "When you don't win games like this, they come back to haunt you."
The Pirates broke a four-game losing streak Wednesday with a 2-1 win over the Chicago Cubs, but they still have lost nine of 12 games and dropped back-to-back series against divisional rivals during a six-game homestand.
"You need the (win), but you've got to go meet the demands of the game," Pittsburgh manager Clint Hurdle said. "There's a lot of people who want to win. You've got to play to win. You've got to figure out how to win.
"Strong win for us."
The pitching matchup in the series opener Thursday -- St. Louis right-hander Jack Flaherty (2-1, 2.15 ERA) against Pittsburgh righty Trevor Williams (5-3, 3.43 ERA) -- will be a rematch from Saturday, a 4-1 Cardinals win.
Flaherty, 22, won his second straight start in that game, going 5 2/3 scoreless innings after giving up a first-inning homer to Starling Marte.
Perhaps more important, Flaherty made a case to remain in the St. Louis rotation with Alex Reyes (who was pulled after four innings during Wednesday's loss to the Brewers) just back from the disabled list and Carlos Martinez due back soon.
"He didn't necessarily need to show us anything," Matheny said of Flaherty's win over Pittsburgh. "We knew he could pitch. ... He's making the right moves in the right direction."
Flaherty has held opponents to three earned runs over his past 19 1/3 innings since he replaced another injured starter, Adam Wainwright.
"It's good to get in a routine and stay in a groove, and help the ball club win every five days," Flaherty said.
Williams gave up four runs and seven hits in just four innings Saturday.
"I think I just had too much plate with all my pitches," Williams said. "We were going for the edges and stuff was leaking out over the plate. ... It was one of those days where my stuff had to be on and, unfortunately, it wasn't."
Williams has given up 15 earned runs over his most recent five starts, and his May ERA is 4.88, with six home runs hit against him.
"He'll bounce back fine," Hurdle said. "This is just part of a major league season."
Williams is 2-1 with a 3.14 ERA in five road starts. He is 2-3 with a 7.16 ERA in eight appearances (five starts) against the Cardinals.