Soto hit off the tee for the first time since going on the disabled list Aug. 7 with a sprained ligament in his right shoulder.
"I think as far as Geo's concerned, he's on track for Sunday, unless there's a setback," Cubs manager Lou Piniella said Wednesday.
Pitcher Carlos Silva, hoping to return to the rotation after undergoing a procedure to correct an abnormal heart rate, threw 40 pitches on the side Wednesday. It was his second bullpen session since he had the cardiac ablation on Aug. 9.
Cubs pitching coach Larry Rothschild was to meet with the medical staff to discuss the next step for Silva (10-5, 3.92 ERA), which most likely will include a Minor League rehab start.