Gallardo, coming off arthroscopic surgery on his left knee, struck out six in 5 1/3 innings for Triple-A Nashville. The Brewers said Gallardo would remain on the 15-day disabled list but rejoin the team in New York on Friday.
"We'll make a determination when we get to New York. We'll see where were at and what's going on. The weather can play into it. We won't take him off until he's needed," Brewers manager Ned Yost said after Milwaukee's 12-4 loss to Cincinnati on Wednesday night.
The main factors in bringing the right-hander off the DL are the weather and an off day during the trip. If Gallardo stays on regular rest, he would be ready to start Monday.
The Brewers are off that day, but heavy rain is forecast throughout the weekend in New York, where Milwaukee opens a three-game series with the Mets on Friday, and if a game is delayed both teams could make it up on Monday.
"It gives us the option to have a guy that would be available if we need to make a move," Yost said.
The Brewers also put Tony Gwynn Jr. on the 15-day DL with a strained left hamstring retroactive to April 4 and called up Hernan Iribarren. Yost said Gwynn is 80 percent right now and he didn't want to risk being short a player or forcing Gwynn into the lineup where he might injure the hamstring even more.
"Let's go ahead and take the eight more days that we need to get it really right without any chances," Yost said.
Gallardo took the loss in his rehab start, giving up two runs and seven hits on 90 pitches, and could make his next start on the upcoming nine-game road trip that also includes stops in St. Louis and Cincinnati.
The Brewers began the spring with eight candidates for the starting rotation. But Gallardo hurt his knee just before camp began, and Chris Capuano is trying to rehab his ailing left elbow instead of another ligament replacement surgery after he had the procedure done in 2002.
"It's going to be a tough decision any way you look at it," Yost said. "It's up to us to decide what's best not only for Dave Bush, but what's best for the Milwaukee Brewers too or Manny Parra or whoever else we decide needs to vacate the final place for Gallardo, but again, we're not there yet."
Gallardo, who made his major league debut June 18, pitched so well down the stretch last year, going 9-5 with a 3.67 ERA with 101 strikeouts in 110 1/3 innings, that he solidified a starting rotation slot even with the injury.