Estrada threw three shutout innings and surrendered four walks and one hit in his first rehab start for Triple-A Nashville on Saturday. The right-hander was placed on the DL on May 25 with a right quadriceps strain.
"His command was a little erratic, but he threw the ball pretty good," Milwaukee manager Ron Roenicke said. "He wasn't missing a lot, but was just off the plate, so he had some walks. He felt good."
Estrada is expected to throw again for Nashville on Thursday with a 75-pitch limit. If all goes well, Estrada will start for the Brewers against Cincinnati on June 26, according to Roenicke. Fiers' impressive string of starts since being called up last month means Milwaukee has no reason to rush Estrada's return, but Roenicke said the club still likes Estrada in its rotation.
Fiers is 2-2 with a 3.60 ERA in four starts.
"It's been talked about," Roenicke said. "I still think that Marco can be a good starter. And [pitching coach] Rick [Kranitz] does too. So that's what our thoughts are right now. But that's not to say that Fiers can't. I've just had a little longer look at Estrada. I like his stuff. I like his command. I think if we can keep him healthy, he can be a good fourth, fifth starter."
The 27-year-old Fiers may still be able to remain on the staff as a long reliever. Southpaw Manny Parra is supposed to assume those duties, but Milwaukee has recently utilized him as a late-inning specialist against left-handed hitters.
"He would give us that length in the bullpen that we're kind of missing," Roenicke said. "It would be kind of nice to have an Estrada or a Fiers in that bullpen to give us length when we need it. If you have a bad start, those guys go in and you don't use everybody."