Jake Westbrook has been trying to ignore elbow pain since spring training.
The St. Louis pitcher and the team finally decided it was time for a break.
"I've pitched through a lot of stuff through my career," Westbrook said Sunday. "It just kind of got a little more inflamed than I would have liked my last start."
The Cardinals will place the right-hander on the 15-day disabled list with elbow inflammation and plan to select the contract of left-hander John Gast in time for Tuesday night's game against the New York Mets.
"I'm 35, so I probably have more problems," Westbrook said. "I don't think it's anything to be super-alarmed about."
General manager John Mozeliak said Westbrook likely would miss two starts after complaining about the elbow in his last outing, but emphasized it was a minor injury.
He said after the 35-year-old pitcher got a cortisone injection on Friday that he'd certainly not be able to make his next start.
"It's really not that big of a deal," Mozeliak said. "It's just something that we didn't want to push it, didn't want it to become a big problem."
Mozeliak bristled at the mention of reconstructive elbow surgery for Westbrook, who missed the postseason last year with an oblique injury.
"Don't put words in people's mouths," Mozeliak said. "He's fine, all right? We knew he couldn't start Tuesday."
Westbrook's last outing was his shortest of the season.
He allowed three earned runs on nine hits in 5 1-3 innings and got no decision in a 5-4 win.
To make room for Gast on the major league roster, the team said injured closer Jason Motte will be moved to the 60-day disabled list while rehabilitating from reconstructive elbow surgery.
Westbrook is 2-1 with a 1.62 ERA in seven starts. His DL move is retroactive to May 9.
The 24-year-old Gast was the team's minor league player of the month in April, going 3-1 with a 1.16 ERA in six starts at Triple-A Memphis.
He began the season with 32 consecutive scoreless innings.