PHOENIX -- Daric Barton's left hamstring strain was revealed to be a mild one Sunday morning, so the A's have deemed the first baseman day to day.
"He'll be day to day," said manager Bob Melvin, "but it's probably going to be several days. Those things, when you get a strain like that, it's something you don't want to mess around with because it could linger the whole season."
It's possible that Barton, who suffered the injury Saturday, will be sidelined at least a week and maybe even longer, considering the typical timetable for these types of strains. That could potentially put a wrench in his push for an Opening Day roster spot as the backup first baseman. He's only compiled nine at-bats, with four hits and four walks.
The A's will continue to get a look at Alberto Callaspo, another potential platoon partner for Brandon Moss, at first base, though Callaspo is set to make the team as one of its most versatile infielders. Nate Freiman, who hit .304 against left-handed pitching last season, is also in the mix.
Barton, the A's longest-tenured player, is out of options and in camp on a non-guaranteed Major League deal.
Jane Lee is a reporter for MLB.com. Read her blog, Major Lee-ague, and follow her on Twitter @JaneMLB. This story was not subject to the approval of Major League Baseball or its clubs.