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2/28/2014 3:37 P.M. ET

Bumgarner takes first step toward opening assignment

SCOTTSDALE, Ariz. -- The motion still began with a deliberate swivel, the left arm still whipped across with power and grace, and the pitch still frustrated the hitters.

Madison Bumgarner was back on the mound, looking as effective as ever.

That was reassuring for the Giants, who will christen the 2014 regular season with Bumgarner facing the Arizona Diamondbacks. Bumgarner worked two shutout innings in his Cactus League debut Friday as San Francisco outlasted the Milwaukee Brewers, 4-3.

"I feel pretty good about where I am right now," Bumgarner said after yielding one hit and striking out two. "Not a whole lot to fine tune."

Nevertheless, Bumgarner will accept every possible opportunity to hone his game before that March 31 Opening Night assignment.

"I feel like every year it kind of takes you the full spring to get to where you want to be, at least for me, anyway," Bumgarner said. "You can do all the bullpens you want -- I don't throw a whole lot before spring -- and you can throw to all the hitters you want [in batting practice], but there's nothing like throwing in a [spring] game. And even that's not like throwing in the regular season. But it's as close as you're gonna get."

Affeldt cautious in getting back into game shape

SCOTTSDALE, Ariz. -- Exercising care after recovering from a sports hernia, left-hander Jeremy Affeldt remains at least a few days away from appearing in a spring game.

Affeldt threw a bullpen session Friday, his first since last Saturday. He said that he'll likely pitch live batting practice on Sunday. At that point, the Giants probably will be able to decide whether Affeldt's ready for game activity or needs a little more work on the side.

Affeldt said that he'll probably need to pitch between nine and 12 innings to prepare adequately for the season. If he has to pace himself to preserve his health, he will. The reliever was perpetually injured last season, enduring a pulled muscle in his right side and a strained left groin as well as the sports hernia.

"I want to make sure all my stuff's ready to go before I go out there," Affeldt said. "I don't mind taking a little extra time. I'd be highly upset if I deal with what I dealt with last year."

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.