CINCINNATI -- Michael Wacha's key to success in his past two starts is finding and maintaining his rhythm on the mound. That was more challenging on Thursday afternoon when rain delayed the start of the game by more than an hour and later created less than ideal conditions on the mound.

"The mound was slick," the St. Louis Cardinals right-hander said. "My foot was sliding a little bit, so between innings I had them put (some drying compound) on the mound."

Wacha overcame the weather to pitch seven shutout innings for the second straight start and second baseman Kolten Wong delivered a two-run single in the fifth, lifting St. Louis to a 3-0 victory over the Cincinnati Reds in the finale of a three-game series at soggy Great American Ball Park.

The start of the game was delayed one hour and eight minutes by rain.

Wacha (13-4) allowed four hits and two walks and had six strikeouts. He has given up one run or fewer in six of his eight career starts against the Reds.

"He had big success with his changeup," Cardinals manager Mike Matheny said. "The curveball was good when they weren't expecting it. His fastball had life, which made the curve even better."

St. Louis (69-39) avoided what would have been its second consecutive series loss to Cincinnati, which hasn't happened since 2011. The Cardinals now are a season-high 30 games above .500.

Cincinnati (48-58) was held scoreless for the final 18 innings of the series, including the last nine in Wednesday night's 13-inning loss.

The Reds have been shut out eight times this season.

"We had six base runners against Wacha in seven innings and four in the last two innings," Reds manager Bryan Price said. "They didn't really give us much to be excited about."

The rain remained steady through most of the game, requiring the grounds crew to regularly apply compound to the mound and the infield.

"It got pretty sloppy," Matheny said. "We were most concerned about the mound, making sure the footing was right."

Wacha was locked in for a second consecutive outing after allowing eight earned runs in his previous two starts.

Cardinals catcher Tony Cruz, inserted into the lineup to give Yadier Molina a rest, delivered a RBI single in the fourth inning off Reds rookie right-hander Michael Lorenzen, putting St. Louis ahead 1-0.

Wong lined a single to center in the fifth, driving in two more runs and making the score 3-0 as the rain persisted.

All three of the Cardinals' runs scored with two outs.

"It was about the big hit today," Matheny said. "We get a two-out hit from Cruz, then a two-out hit by Wong. That was the difference."

Lorenzen (3-7) allowed three earned runs, four hits and four walks in five innings. It was the fifth start in his past six in which Lorenzen has walked three or more batters.

"I didn't have bad stuff," the 23-year-old Lorenzen said. "I didn't the last time out either. I felt good. I thought I threw the ball really well. This is just my second year as a starter. Every start is a new experience. I just have to keep at it and keep moving forward and keep my chin up."

Cincinnati brought the tying run to the plate in the eighth and ninth.

Reds third baseman Todd Frazier made a bid to tie the score when he flied out to the warning track in center against the Jonathan Broxton in the eighth.

"The park played big today," Price said. "Frazier's drive could've been a difference-maker on a normal day."

In the ninth, Cardinals closer Trevor Rosenthal struck out pinch-hitter Brayan Pena and second baseman Brandon Phillips to finish off his 32nd save of the season.

Having to cover just two innings with the bullpen was ideal for the Cardinals after they used all but one available arm during Wednesday's marathon.

"Best recipe we could have is getting Wacha through seven," Matheny said.

NOTES: The Cardinals posted their 11th shutout victory this season. ... Cardinals C Yadier Molina and SS Jhonny Peralta were given the day off on Thursday, largely because of playing 13 innings the night before and having a day game after a night game. ... Cincinnati has had 19 rain delays this season, including 13 at home, totaling 24 hours and 40 minutes with three postponements and one suspension. ... With CF Randal Grichuk's 20th double in Wednesday night's game, he became the fifth Cardinals batter this season with that many. ... The Reds haven't won consecutive series against St. Louis since 2011.