Infielder Scooter Gennett was optioned to Nashville after Tuesday's 3-1 victory in San Francisco to open a roster spot.
What is at stake for Estrada in what remains of the regular season?
"My job," he said after arriving at AT&T Park on Tuesday afternoon. "I mean, I don't see why it wouldn't be. It's been two months since I've pitched. I've got to show them I can still do it. I've been keeping up with guys and I see that everyone is pitching really well now. Obviously I've got to fight for my job, and hopefully, they like what they see."
The Brewers liked Estrada so much in 2012, when he posted a 3.64 ERA in 29 appearances (23 starts) that they lined him up to pitch the second game of 2013. But he pitched to a 5.32 ERA in his first 12 starts before suffering a strained hamstring in a June 3 start against the A's.
His role for 2014 is up in the air. Estrada is earning $1.955 million this season and will be arbitration-eligible for the second time.
"It's important for him to finish up well," Brewers manager Ron Roenicke said. "We know he can also go to the bullpen, but it's important for him to finish up well if he wants to continue starting, to show us what he did last year. It's different this year. I don't know why, but it's different."
Estrada is used to fighting for his job. Before this past spring, he had never been assured a spot in a professional starting rotation.
"I've been dealing with it my entire life," Estrada said. "Last year was probably the first time I felt like I was going to be OK [in terms of having a roster spot], and even this season I felt like I was going to be OK. But with this injury now, you start thinking about it. I'm trying not to think about it too much, but it's there. I know I've got to come out and do my job, and if they don't think I'm ready then who knows what's going to happen? But hopefully I show them that I'm ready to pitch here and hopefully they'll want me here."
Estrada's return from the DL was delayed by back tightness, but on Tuesday he declared himself fit to pitch. He was supposed to make one more Triple-A start Wednesday, but the Brewers accelerated the schedule in the wake of Gorzelanny's injury.
Gorzelanny will rejoin the rotation when he is ready, Roenicke said, instead of going back to the bullpen. Gorzelanny is scheduled to throw a bullpen session Wednesday, and the result will dictate where he is slotted back into the rotation, probably at Donovan Hand's or Tyler Thornburg's expense.
"I think [Gorzelanny] is a possibility for next year, and the more we see of him right now, it's easier for us to make a decision on next year," Roenicke said.