Lance Lynn is in St. Louis' starting rotation because Chris Carpenter is on the disabled list.
The replacement is certainly doing his best imitation of a Cy Young award winner.
Lynn looks to win his fourth consecutive start and help the Cardinals avoid being swept by the Chicago Cubs for the first time in two years in Wednesday's series finale at Wrigley Field.
After pitching primarily in relief as a rookie last season, Lynn (3-0, 1.42 ERA) is getting a chance to start with the 2005 NL Cy Young winner sidelined due to a nerve problem in his pitching shoulder.
Lynn has made the most of his opportunity, yielding one run in each of his first three starts and winning them all. No St. Louis pitcher has won his first four starts in a season since Joel Pineiro in 2009.
Against Pittsburgh on Friday, Lynn gave up four hits and struck out four in seven innings of a 4-1 victory.
"What I did when they moved me to the bullpen last year was challenge hitters, get ahead in the count and make them hit my pitch,'' said Lynn, who has struck out 17 and walked four in 19 innings. "I'm more aggressive and more confident now as a starter.''
This will be his second start against the Cubs (6-12) after permitting four hits - two to Alfonso Soriano - in 5 1-3 innings of a 5-1 home win April 14.
The Cardinals (11-7) took two of three in that series but have dropped the first two at Wrigley this week on a pair of late rallies. They haven't been swept by the Cubs since Sept. 13-15, 2010, and haven't been swept at Wrigley since dropping all four games July 27-30, 2006.
Joe Mather hit a two-run single with two outs in the ninth Tuesday to give the Cubs a 3-2 victory, and Soriano delivered a game-ending RBI single in the 10th on Wednesday to beat the Cardinals by the same score.
Bryan LaHair sent the game to extras with a solo shot in the ninth after Matt Holliday hit a two-run homer off Carlos Marmol in the eighth to put St. Louis ahead 2-1. LaHair's homer was the first by a Cub since he hit a grand slam in a 9-5 win at St. Louis on April 13.
"It's huge, especially against one of the best teams in the National League, and the world champions,'' Chicago manager Dale Sveum said. "To do it in that fashion gives the guys in that locker room confidence.''
With the victory, the Cubs won their first series in six tries under Sveum.
The loss, meanwhile, ended St. Louis' run of 13 consecutive winning series, the longest such streak in the majors since the 2002 Atlanta Braves.
The Cardinals, who could have won Tuesday had a couple of close calls gone their way, will try to bounce back against Chris Volstad (0-2, 6.19), who also opposed Lynn earlier this season.
In six innings of work at Busch Stadium two weeks ago, Volstad gave up four runs and six hits. The right-hander had another tough go in his next start against Cincinnati, yielding six runs and seven hits in five innings of Friday's 9-4 loss to Cincinnati.
That marked his seventh defeat in 14 starts since his last win, which came against Houston on July 10.
Holliday and Yadier Molina are each batting .429 in 14 at-bats against Volstad.