PHOENIX – San Francisco Giants starting pitcher Matt Cain, who had season-ending elbow surgery last August, was placed on the team’s disabled list with a strained tendon in his throwing arm just one day into the 2015 season.

Meanwhile, Cain’s fellow starter Jake Peavy is missing his Tuesday start against the Arizona Diamondbacks with back stiffness, and will be replaced by Ryan Vogelsong, a starter last year who is now a relief pitcher.

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Cain underwent an MRI Monday to confirm the diagnosis of a strained flexor tendon but no ligament damage, as had been feared.

He told CSN Bay Area the Giants trainers seemed positive about the prognosis.

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“It’s definitely frustrating, but it goes with the territory” Cain told CSN Bay Area. “There are some bumps in the rehab process. This is one of them.”

The 30-year-old Cain’s surgery last year was to remove bone chips and spurs. He could miss up to two weeks.

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Peavy is expected to return for his next turn in the rotation. Cain’s Wednesday turn could be taken by either remaining starter Tim Hudson or Tim Lincecum, or the Giants could promote a minor leaguer for the week. Reliever Yusmeiro Petit is also a candidate for a spot start.