The Phillies and Cardinals open a three-game set on Monday night at Citizens Bank Park.
The teams are meeting for the second time in a month after splitting a four-game series in May at Busch Stadium.
Pivetta (4-6, 4.25 ERA) has an 8.36 ERA and opponents are hitting .352 with a .940 OPS against him through three June starts. The 25-year-old had a 3.26 ERA and .230 batting average against during his first 11 starts of the season.
Pivetta's hardships were evident in his last start.
Facing the Colorado Rockies, he allowed six runs, eight hits and three walks in five innings of a 7-2 loss on Wednesday. It was the fourth straight start in which Pivetta took a loss.
"I think that his composure hasn't been perfect, but he's a young, developing pitcher," Phillies manager Gabe Kapler told MLB.com after Pivetta's start. "He's going to have his bumps. He's going to have hiccups along the way. I think this is just an indication of that."
Pivetta did not pitch against the Cardinals when the Phillies faced them last month, but he saw St. Louis twice last year. Pivetta allowed seven earned runs and struck out 12 in 11 combined innings during those starts.
Pivetta will be facing a Cardinals team that posted a 5-0 victory over the Chicago Cubs on Sunday night but still has lost five times in its last seven games. The Cardinals (37-32) enter the series four games behind the first-place Milwaukee Brewers in the National League Central.
Right-hander Miles Mikolas (7-2, 2.43 ERA) will be on the mound in the series opener. Mikolas, who spent the last three seasons pitching in Japan, leads the Cardinals with a 0.96 WHIP and his 2.43 ERA is the best in their rotation.
The Cardinals are 9-4 in Mikolas' starts, but they lost in his last outing. He gave up three runs and six hits in six innings against the San Diego Padres in a 4-2 loss on Tuesday.
"He was throwing the ball well, and he came back and threw the ball well [after a three-run inning]," Cardinals manager Mike Matheny told reporters after Mikolas' last start. "He's on a nice roll."
The Phillies are looking for their third series victory in a row. They are returning home for three games against the Cardinals after taking two of three against the Milwaukee Brewers over the weekend.
Philadelphia was a 10-9 winner over Milwaukee on Sunday as Maikel Franco went 2-for-3 with a home run and four RBIs. The third baseman was making just his second start since June 6 and homered for the first time since May 26.
"Mikey has shown an incredible attitude recently," Kapler said when he met with reporters after the victory. "He's come to the ballpark and prepared, even when he has not been in the lineup."
Rhys Hoskins also homered and is batting .333 (10-for-30) with four homers and 11 RBIs since returning from a broken jaw.