Soto, batting .288 with 15 homers and 45 RBIs, has not played since Aug. 6.
Carlos Silva, who underwent a procedure Aug. 9 to correct an abnormal heart rate, was to throw Wednesday on the side at Wrigley Field. The right-hander, who is 10-5 with a 3.92 ERA, could be scheduled for a rehab outing if all goes well.
First baseman Derrek Lee was expected back in the lineup Thursday after having an epidural injection in his lower back. Lee, who was batting .251 with 16 homers and 56 RBIs, came out of Sunday's game because of his back.
Reliever John Grabow was examined by team orthopedic specialist Stephen Gryzlo on Monday, and they were deciding whether to have surgery on his left knee. Grabow has been limited to 28 games because of a sprain.