(SportsNetwork.com) - Michael Wacha has gotten off to an amazing start in 2015. His history of success at Busch Stadium is also marvelous.

Wacha takes his 4-0 record to the mound Sunday afternoon when the St. Louis Cardinals try to complete a three-game sweep of the Pittsburgh Pirates.

The Cardinals, winners of five in a row, have pulled out 2-1 wins in extra innings in each of the first two contests this weekend.

Wacha, who has won each of his four starts in 2015, allowed just five hits and one run in each of his first three appearances until giving up six hits and four runs in his last outing, against the Phillies on Tuesday. He is 9-1 with a 2.45 ERA in 21 games (17 starts) all-time at Busch Stadium.

In three games (2 starts) versus the Pirates, Wacha is 1-0 with a 1.93 ERA.

Vance Worley counters on the hill for Pittsburgh. The righty is coming off a 4-0 loss at Wrigley Field on Monday when he allowed nine hits and all four runs in six frames.

Worley has made three starts versus the Cardinals and is 0-0 with a 4.96 ERA.

On Saturday, Matt Carpenter's sacrifice fly in the bottom of the 11th brought home the winning run for the Cardinals.

Peter Bourjos started the deciding frame against Jared Hughes (0-1) with a double, but was caught stealing third. Pete Kozma singled and Jon Jay kept the rally alive on a base hit which put runners on the corners. Carpenter easily plated Kozma with a long fly to left.

It made a winner of Carlos Villanueva (3-1) who allowed a hit and a walk in the top of the 11th but remained unscathed.

Bourjos ended up with two of the six hits for the Cardinals.

"I'm really happy about how guys just keep playing," Cardinals manager Mike Matheny said. "Somebody's coming up big and today we had a couple of guys. It's fun when you can pull those out."

John Lackey ended up allowing a run on six hits with four strikeouts and three walks over six innings.

Starling Marte collected three hits, Gregory Polanco added two and a run scored with Josh Harrison knocking in the lone run for the Pirates, who have lost four of their last five.

Pittsburgh went 1-for-13 with men in scoring position and left 18 runners on base.

"We're not going to do anything different," Pirates manager Clint Hurdle said. "When you play the game every day for six months you're going to go through some stretches where you get challenged."

A win Sunday would give the Cardinals an 18-6 start, which would match their best beginning to a campaign since 1944. The only other time the Cardinals were 18-6 was in 1941.

The Pirates were 2-8 at Busch Stadium last season and have gone 5-16 the past two-plus seasons in St. Louis.