"We haven't looked at it deeply but it could happen," Sveum said before the Cubs took on the Colorado Rockies on Tuesday night.
Garza will make a rehab start for Triple-A Iowa on Thursday and then a determination will be made if he's ready to be activated.
"I'm not looking forward to anything past Thursday," Garza said.
If Garza can get into or beyond the sixth inning without his pitch count being too bloated he might be ready to return to the rotation and that's when Sveum will have to make a decision. A six-man rotation is far from a given.
"It's a tough decision because everyone has pitched pretty well and it's going to be one of those things, it's going to be unfortunate for somebody," Sveum said. "Maybe you go to a six-man rotation for a week just because of matchups. You never know. A lot of things come into play."
Sveum was asked if current performances by starters, such as Carlos Villanueva on Tuesday, will help determine who's in and who's out.
"It's not a tryout camp," he said. "We'll cross that bridge after he pitches on Thursday."