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8/31/2013 2:45 A.M. ET

Cain plans to return next Saturday

PHOENIX -- Giants right-hander Matt Cain said Friday that he expects to pitch as soon as he's eligible for activation from the 15-day disabled list, which will be next Saturday, Sept. 7, at AT&T Park against Arizona.

"That's the plan," Cain said.

Cain sustained a bruise on his throwing arm when he was struck by a line drive hit by Pittsburgh's Gaby Sanchez on Aug. 22, forcing him onto the DL for the first time in his eight-year career.

Cain expects to test his arm Saturday by throwing off a bullpen mound for the first time since being injured. He has spent the week at the Giants' training complex in nearby Scottsdale, Ariz., undergoing treatment and throwing on flat ground at distances up to 100 feet.

Pagan makes difference in first game back

PHOENIX -- Angel Pagan rejoined the Giants two days ahead of schedule on Friday, feeling confident that he had healed sufficiently from a left hamstring surgery.

Manager Bruce Bochy seized the opportunity to use Pagan, installing him in center field and at the leadoff spot for the series opener against the D-backs.

Pagan did exactly what Bochy and the Giants hoped he would, doubling in his first at-bat and sccoting home on Brandon Belt's sacrifice in the first inning to account for the only run in the Giants' 1-0 win.

"I'm glad we decided to bring him [back] a couple of days earlier, or we might still be playing," Giants manager Bruce Bochy said, joking.

Added Pagan: "That was my purpose, coming here and trying to bring as much energy as I can."

Pagan's explanation for his accelerated comeback was simple: He felt ready to perform on the Major League level, after missing 84 games and watching the Giants plummet from first place to last in the National League West. After Pagan lobbied head athletic trainer Dave Groeschner earlier this week to let him return before the expected date of Sept. 1, the Giants relented.

"Right now, I want to say I feel 90-95 percent," said Pagan, 32. "But there's no way I can feel 100 percent this fast. This is part of the rehabilitation. But I feel great to play and to be the same player that I was before I got hurt."

Pagan hit .262 with three homers and 24 RBIs in 46 games before being sidelined. His last act during his early-season stint was hitting a two-run, inside-the-park, game-winning homer against Colorado on May 25. He underwent surgery exactly one month later.

"This is something I have to keep an eye on maybe for the rest of my career," Pagan said. "It doesn't bother me, because I work really hard, take care of my legs a lot, do a lot of stretching. The stretching is one of the things you have to be involved in with this type of injury, and I have no problem with that. I stretch two, three times a day."

Once cleared to play, Pagan prepared for his return by hitting .241 (7-for-29) in nine Minor League injury rehabilitation outings with the Giants' squad in the Rookie-level Arizona League and with Triple-A Fresno.

Though Pagan's statistics looked ordinary, the switch-hitter said, "I just felt the at-bats I took in Triple-A were productive, and I felt good at the plate."

Pagan contributed significantly to the Giants' World Series-winning effort last year. He batted .288 with career bests in runs (95), doubles (38) and triples (15). He also scored 10 runs in 16 postseason games.

To clear room for Pagan on the active roster, the Giants optioned outfielder Francisco Peguero to Fresno. They created a 40-man roster spot for Pagan by transferring outfielder Andres Torres from the 15-day disabled list to the 60-day DL.

Petit, Zito swap rotation spots

PHOENIX -- The Giants made a minor adjustment to the sequence of their starting rotation, announcing Friday that right-hander Yusmeiro Petit will pitch Sunday against Arizona, followed by left-hander Barry Zito on Monday at San Diego.

Zito had preceded Petit in the rotation. But, said manager Bruce Bochy, "We wanted to give Barry a couple of extra days [of rest]."

The remainder of the rotation remained unchanged.

Petit played for Arizona from 2007-09, mostly as a starter. He posted a 9-19 record with a 5.05 ERA in 56 appearances, including 35 starts.

Chris Haft is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.