That could change, however, as the left-hander is still feeling tightness -- and not soreness -- in the triceps after three days of rehabilitation.
Stults played catch before Sunday's game with the Mets. Black said a determination could be made on the starter as soon as Sunday or possibly Monday in Chicago.
"We're hoping for the best," Black said.
Stults was limited to five innings in Thursday's victory over the Mets.
If Stults can't make this start, the Padres wouldn't have to reach into the Minor Leagues for a short-term replacement -- right-hander Matt Palmer would likely get the start.
Palmer, who was recalled from Triple-A Tucson on May 20 to give the team a long reliever, made seven starts with Tucson before joining the Padres. He had a 4.64 ERA in those starts. He's allowed two runs in three games with the Padres thus far.