"We have to play the hand we're dealt with here," manager Walt Weiss said.
Anderson lasted just three innings Saturday after bruising the index finger on his left hand apparently while grounding out off Giants starter Matt Cain to end the top of the fourth. Anderson took the mound to begin the bottom of the frame and threw one warm-up pitch before a team trainer was summoned from the dugout.
"It felt like a firecracker went off in my glove," said Anderson, who is 0-2 with a 3.60 ERA in three starts this season. "I went out there and threw a warm-up pitch, and it felt like what I envision trying to throw with a foam finger feels like."
Weiss confirmed the injury Sunday, and it's likely that Anderson will land on the disabled list after he sees a hand specialist in Denver on Monday.
It is yet another injury setback for the 26-year-old who last worked as many as 100 innings back in 2010. Anderson missed the majority of the 2011 and 2012 seasons after elbow surgery and then was out most of last season with a broken bone in his foot.
The Associated Press contributed to this report.