Garza (5-7, 3.91 ERA) threw a full bullpen session on Saturday, and the Cubs will wait to see how the right-hander feels on Sunday before saying for sure who will start.
"I'm just champing at the bit and ready to go," Garza said. "Not doing anything for three days didn't set me back but didn't work out too well. Today I felt great, threw a whole bullpen and we'll wake up tomorrow."
Garza was sidelined while with his wife, who gave birth to the couple's fourth child on Tuesday in Chicago. The only issue may be stamina. In his last start, Garza threw 33 pitches before he was pulled.
"Even if he goes [Tuesday], it won't be all that many pitches," Cubs manager Dale Sveum said. "If he goes, it would be 70 to 80 pitches and depend on the stress level. [His session Saturday] was encouraging."
The Cubs may have a Minor League pitcher waiting in the wings in case Garza isn't ready.