ST. LOUIS -- The Brewers brain trust laid out a long list of scenarios Thursday morning, but came no closer to deciding how to get right-hander Yovani Gallardo back into the starting rotation.

"We haven't decided yet," manager Ned Yost said. "We're talking through things, making sure we have everything in a row."

Gallardo is ready to return from his left knee injury, but someone else must be bumped from the rotation to make room. Ben Sheets and Jeff Suppan are listed as the team's probable starters Friday and Saturday in Cincinnati, but the team continues to list "TBA" for Sunday, when it would be Dave Bush's turn. That makes it very likely that Gallardo will pitch that day.

Among the possible scenarios to clear a spot:

• Bump Bush, who is 0-3 with a 7.02 ERA, to the bullpen, where he has some experience both in the big leagues (27 relief appearances as a pro, plus time as a collegiate closer), or to Triple-A Nashville. Bush has a Minor League option remaining and the Brewers have already passed him through the option waivers necessary to make the latter move with a player of Bush's level of big league service.

In fact, the Brewers and other teams request waivers on most of their players that last for six weeks, according to general manager Doug Melvin. There is a gentlemen's agreement among GMs that teams don't claim those players, because they could just be pulled back and it would gum up the whole system.

• Leave Bush in the rotation and move right-hander Carlos Villanueva to the bullpen. He had success there last season, though he prefers starting and appears more effective in that role. A long first inning doomed Villanueva to a poor start on Wednesday against the Cardinals in which he surrendered five runs in 4 2/3 innings.

• Leave Bush in the rotation and option either Villanueva or left-hander Manny Parra to stay on a starting routine in the Minors. Parra started Thursday's series finale against St. Louis.

Gallardo, meanwhile, is staying patient. He threw his usual between-starts bullpen session on Wednesday and said he's ready, whether he starts Sunday in Cincinnati on Monday or Tuesday against the Cardinals in Milwaukee.

"I'm excited to get going," said Gallardo, who underwent knee surgery on Feb. 19.

The Brewers might not announce their decision until Saturday. On Thursday, Yost appeared to give a vote of confidence to Bush, who allowed three runs in six innings of Tuesday's loss to the Cardinals.

"Bush has [produced] in the past, and for me, Bushy is a guy that is very durable, a great competitor, a guy that is a 200-innings-a-year guy. Those are very valuable. He needs to refine some mechanics and he started that here [on Tuesday], and when he was consistent with what they were working on, his stuff was really, really good. It does help the command of his fastball, which is key."

Gallardo is expected to be a key part of Milwaukee's pitching rotation this season. He went 9-5 with a 3.67 after a midseason promotion from Nashville in 2007.