Anderson left Sunday's game in Pittsburgh with tightness in his left quadriceps and has been listed as day-to-day. He didn't play in Monday's 3-2 loss against the Nationals and wasn't in the lineup for Tuesday's game.
"We've got to reevaluate him," Cox said. "We're short on players, so we can't wait forever to have him get well on the active roster. We'll have to see him how this goes the next couple [or] two days."
Anderson came to the Braves this year as a free agent after playing with the Angels since 1994, his rookie season, and has battled a few injury problems.
A strained right calf held him to just seven games in Spring Training, but Anderson still hit .300 (6-for-20). The calf also caused him to be scratched from the starting lineup at the Phillies on April 8, but Anderson returned six days later. He made two pinch-hit appearances before making it back to the starting lineup.
Anderson was a solid hitter while playing with the Angels from 1994-2008. He came to the Braves with a .296 career average in 2,013 career games.
That's why Cox is hopeful that the Braves can keep him active.
"We'll see how it's coming along," Cox said. "We hate to put him on the disabled list, because he could be such a force in our lineup. He really can hit [and is a] good-looking hitter."
Injuries have hurt the Braves throughout the early part of this season. Pitchers Tom Glavine (left shoulder) and Jorge Campillo (right rotator cuff) have been out, while catcher Brian McCann (blurred vision) has missed time.
Yunel Escobar returned Monday after being out since Thursday with a strained abdominal muscle. Chipper Jones missed four straight games with a bruised left thumb before returning Sunday. David Ross (strained right groin) sat out the first eight games. Jordan Schafer has battled left hand/wrist problems but has stayed in the lineup.
"We haven't had our team in the lineup," Cox said. "We haven't really seen our team yet, but we have a good team."
Jeff Seidel is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.