ST. LOUIS - The pressure of pitching in a pennant race in September does not seem to be affecting Michael Wacha.
The Cardinals' 22-year-old rookie made the sixth start of his career Sunday and worked seven scoreless innings in pitching the St. Louis Cardinals to a 9-2 victory and a sweep of their three-game series against the Pittsburgh Pirates.
The Cardinals came into the series a half-game behind the Pirates in the National League Central and finished it with a 1 1/2 game lead, thanks mainly to the performances of their three starting pitchers.
In the three-game set, St. Louis starters combined to allow the Pirates just one run in 20 innings. Joe Kelly allowed one run in six innings Friday and Adam Wainwright hurled seven shutout innings Saturday night.
The Cardinals staked Wacha to a 5-0 lead after the first two innings.
"I've played in some big-time games before, in college," said Wacha, who 16 months ago was still pitching for Texas A&M. "This is a little bit different, for sure, but playing in those big time games at A&M gets me prepared for it. I just try not to think too much and just go out there and trust my stuff. It worked out pretty well."
Wacha was never in trouble, allowing just two hits -- a bloop double by Jordy Mercer that barely landed in fair territory with one out in the third and a one-out single by Andrew McCutchen in the seventh. Wacha walked two batters, one in the fourth and one in the fifth, but both were erased in double plays.
Wacha entered the game with a scoreless streak of 12 2/3 innings over his last four appearances, including six shutout innings in his last start against the Cincinnati Reds on Wednesday, the other team the Cardinals are battling in the division. In Wacha's six career starts, he has allowed two runs or less five times. In his two September starts, Wacha has pitched 13 scoreless innings.
His current streak of 19 2/3 consecutive scoreless innings matches the longest streak by a Cardinal pitcher this year, accomplished by Kelly from July 12-Aug. 6.
"Today was just a phenomenal job by him," said second baseman Matt Carpenter. "To get a guy as young as he is, and pitching in such a big series with a sweep on the line, and to go out and just dominate was impressive. He's a special player. He's tough on hitters, and you saw that today."
The Pirates came into the series needing just one win for their 82nd victory of the season, and their first winning year since 1992, but could not get that win in St. Louis as their losing streak reached four games, tying their longest streak of the season. They were shut out for the first eight innings and finally ended a 17-inning streak without a run with two runs in the ninth.
"We weren't sharp in any particular area of the game all weekend," Pittsburgh manager Clint Hurdle said. "They were much sharper than us across the board. The part of it that we hold onto is that we will be in Texas tomorrow and out of St. Louis. We've just got to go play. The season doesn't stop. We've got every opportunity to get things rolling back the way we want."
The Pirates also lost starting pitcher Charlie Morton, who was forced to leave the game with two outs in the second because of what was announced as discomfort in his left foot. He is returning to Pittsburgh to undergo further medical evaluation Monday.
NOTES: The Pirates had 2B Neil Walker hitting leadoff for only the second time this season and second time in his career. He also hit in that spot Sept. 1 against the Cardinals. The Pirates have used four players in the leadoff spot since Starling Marte was hurt Aug. 18. ... Allen Craig, who has missed the Cardinals' last four games because of a sprained left foot, was walking without the boot in the clubhouse before the game. He was able to put some weight on the foot. There is no timetable on when he might be able to play. ... The Cardinals will have Monday off before hosting Milwaukee on Tuesday, while the Pirates will open a three-game series in Texas against the Rangers. Gerrit Cole will pitch against Yu Darvish. The Pirates are 0-6 in games played at Arlington. ... The Pirates have only one remaining day off this season, on Sept. 26.