SCOTTSDALE, Ariz. -- Giants second baseman Marco Scutaro's playing status for the start of the regular season is 50-50 at best due to his ailing back, manager Bruce Bochy acknowledged Thursday.

Scutaro, 38, received an epidural shot Thursday to relieve his discomfort. Bochy said that the Giants will wait two days to allow the shot to take effect before Scutaro is re-evaluated. "I think we have to be smart with what we do now," Bochy said.

Bochy insisted that after this period, Scutaro still would have sufficient time to get enough at-bats and prepare himself physically for San Francisco's March 31 season opener at Arizona.

Asked whether Scutaro's availability for the opener is a long shot, Bochy replied, "Oh, boy. ... I don't know if it's quite a long shot, but it couldn't be more than 50-50."

Expected to anchor the No. 2 spot in the Giants' batting order, Scutaro struggled to remain optimistic after Thursday's injection. After reiterating his now-familiar remark about the fickle nature of back health, he said, "It's just a matter of getting the inflammation down a little bit and we'll be fine."

Scutaro hasn't been fine despite receiving a painkilling injection earlier this spring. After playing in 127 games last year, he complained of back problems upon reporting to camp in mid-February. After increasing his activity in workouts, Scutaro made his Cactus League debut last Monday against the Angels, doubling on his first swing and going 1-for-2 while playing three innings.

Since then, Scutaro hasn't appeared in a game.

Bochy said that if Scutaro feels fit enough to begin the season on the active roster instead of the disabled list, he probably would appear in Minor League exhibitions just to get at-bats and play in Cactus League games, as well as next week's Bay Bridge Series, to sharpen himself defensively as well as offensively.

Bochy indicated that Joaquin Arias, who started at second base in Thursday night's exhibition against San Diego at Peoria, Ariz., likely would man the position if Scutaro can't play. The Giants also still have Tony Abreu, Ehire Adrianza and non-roster invitee Brandon Hicks in camp. "We're going to try to mix it up," Bochy said, hinting that Abreu, Adrianza and Hicks will have further opportunities to prove themselves. "But we think Joaquin is a good answer."

But the Giants must watch the calendar. Players can go on the disabled list for a maximum of 10 days retroactively before Opening Day, thus enabling them to miss only five regular-season games. But appearing in a Major League exhibition after this weekend would increase the number of regular-season games Scutaro would miss.

Arias proved especially handy in August 2012 when he hit .417 as injured third baseman Pablo Sandoval's fill-in. He entered Thursday batting .333 in 12 Cactus League games, eclipsing Abreu (.158) and Adrianza (.194). Hicks has been a pleasant surprise, taking team highs in batting average (.419), RBIs (10), on-base percentage (.525) and slugging percentage (.839) into Thursday.

But the Giants were hoping for a healthy season from Scutaro, who accelerated the Giants' march to their 2012 World Series triumph. After obtaining Scutaro from Colorado that July, he quickly became renowned among his new teammates for advancing baserunners, avoiding strikeouts and driving in key runs. He collected 44 RBIs in 61 games and batted .362 before being named Most Valuable Player of the National League Championship Series against St. Louis. Scutaro also delivered the 10th-inning single that scored Ryan Theriot with the go-ahead run in Game 4 and helped the Giants complete their World Series sweep of Detroit.

Scutaro's efforts prompted the Giants to sign him to a three-year, $20 million deal during the 2012-13 offseason.