SCOTTSDALE, Ariz. -- Zack Greinke's return has been considered relatively open-ended, but the best-case scenario of him returning for the April 16 start is likely out of the picture now, Brewers manager Ron Roenicke said Friday.

"If he's ready at that point, I'm going to be really happy," Roenicke said. "I just don't know if he's going to be ready then. I think we're not really planning on that early."

Greinke has yet to play catch. He has been doing cardiovascular training, elevating his heart rate to the point where he feels the rib injury, Roenicke said.

The Brewers' quest for a starter to fill in for Greinke into the regular season got more complicated Friday in the span of eight hitters.

Wily Peralta, the 21-year-old right-hander who has been considered the likely frontrunner for the temporary spot, recorded just one out and surrendered three doubles that led to five runs before Roenicke pulled the plug.

"It's the same thing, just coming in and, whether it's the big-league setting and he thinks he needs to make a good impression, whatever it is, he's not himself," Roenicke said. "We need to get him to relax and pitch the kind of ballgame we know he can. Hey, at that age, I don't know if I could do that, either."

Peralta's high pitch count in the inning, which included a pair of walks, was the primary reason he was lifted, Roenicke said.

If it's not Peralta who grabs the spot, non-roster invitees Eulogio De La Cruz and Marco Estrada are among the possibilities that have been mentioned, along with Amaury Rivas and Mark Rogers -- both on the 40-man but optioned to Minor League camp earlier this week.

Brewers playing it safe with Marcum

SCOTTSDALE, Ariz. -- The day after he was pulled early from his Cactus League start with shoulder tightness, Shaun Marcum had a message for manager Ron Roenicke when he saw him Friday morning.

"He just told me he didn't want me to worry about it," Roenicke said.

Marcum did some work with the team's medical staff Friday, and more will be known in the coming days about how to much his ailment will set him back. Marcum had been experiencing tightness in the shoulder this spring, and it was determined the safest route to have him exit Thursday's game after just three innings.

"Whether we just push him back or whether we skip and go to the next start ... probably that's what will happen," Roenicke said, referring to the latter scenario.

Roenicke does have some concern about what happens if indeed Marcum needs to be shut down for an extended period of time. The Brewers have enough to contend with already with ace Zack Greinke on the shelf probably at least halfway through April.

"We're trying to figure out who's going to be the fifth [starter]," Roenicke said. "It'd be hard to figure out if we need to get one more."

Last call

Mat Gamel made his first appearance in the field of the spring after being sidelined by a rib-cage strain, entering the game in the late innings at third base. After he tied the game in the top of the eighth with an RBI single, he untied it with a throwing error in the bottom of the eighth of a 9-7 loss to the Rockies. Roenicke chalked up the error, in part, to rust. "We look for a lot of offense from him, and he gave us a really nice at-bat," he said. "So if he makes the mistake at third like that, we want him to just go make the play the next time instead of thinking about what happened on that one." ... Many of the Brewers' projected regulars got a chance to play together in Friday's game, and all of them managed to get base hits -- the biggest of which was a three-run rocket into the grass berm in right-center field by Prince Fielder, his third homer of the spring. Carlos Gomez and Yuniesky Betancourt had coubles and Ryan Braun had a pair of singles. ... Right-hander Tim Dillard did an admirable job of shutting down the first inning after young Wily Peralta struggled, and wound up going 2 2/3 innings of shutout ball, striking out two.