PHOENIX -- Only two games into the regular season, the Giants appeared destined to add a second starting pitcher to the disabled list.
As expected, right-hander Matt Cain went on the 15-day disabled list Tuesday, retroactive to April 4, with a strained flexor tendon in his throwing arm. The Giants recalled rookie right-hander Chris Heston to replace Cain as Wednesday's starter against the Arizona Diamondbacks.
After Tuesday's 7-6 loss to the D-backs, Giants manager Bruce Bochy revealed that right-hander Jake Peavy, who was scheduled to start the game but was scratched with lower back pain, continued to feel discomfort after a bullpen throwing session. This increased the likelihood that Peavy would join Cain on the DL.
"I don't think it's crazy serious," Peavy said of his malady. But he admitted that he lacked sufficient range of motion as he threw.
"I'm not a fan of the disabled list, and I'll do all I can to stay off it," Peavy said. "Still, I have to do what's best for the ballclub."
Bochy said Cain soon will return to San Francisco to be re-evaluated by team doctors. Following that examination, the Giants should have a more accurate estimate regarding the length of time that Cain will be shelved.
This marked Cain's fifth trip to the DL since August 2013.
"It's unfortunate for Matt," Bochy said of Cain, whose 2014 season was shortened by August elbow surgery to remove bone chips and spurs. "He worked hard to get back on the mound."
Heston, who turns 27 on Friday, would have started Sacramento's inaugural game as the Giants' Triple-A affiliate Thursday.
"You don't really expect to get called up before the [Minor League] season even starts," he said.
Heston appeared in three games with the Giants last September and started one, allowing three runs in four innings against San Diego on Sept. 28 in the regular-season finale. He believed that experience should help him stay calm against the D-backs.
"Hopefully, some of those pregame jitters will be [gone]," Heston said. "But I'm sure I'll still have some butterflies going on."
The performance Heston would prefer to build upon was his March 27 Cactus League outing against the Dodgers, whom he limited to three runs (two earned) and four hits in six innings while facing a lineup composed mostly of everyday players.
"If you have a little bit of success, it definitely helps your confidence," he said. "I'll try to ride it as long as possible."
Chris Haft is a reporter for MLB.com. Read his blog, Haft-Baked Ideas, and follow him on Twitter at @sfgiantsbeat. This story was not subject to the approval of Major League Baseball or its clubs.