Still with the NL's best record despite an awful stretch, the Brewers now could reach a new low point. They haven't been swept in a series of more than two games all season but could be dealt a four-game sweep by the last-place Philadelphia Phillies, who had traveled to Miller Park amid a big slump of their own.
Milwaukee (52-40) has lost four straight and eight of nine, with the only victory coming Saturday when Garza fired a two-hitter in a 1-0 victory at Cincinnati.
If Garza's hot stretch doesn't continue - he's 4-1 with a 2.36 ERA in his last seven starts - the Brewers could suffer a season-high fifth consecutive loss. That would only further damage their confidence going into a weekend series against division rival St. Louis, the defending Central champion which is now within two games of Milwaukee.
"We're just in a funk right now," manager Ron Roenicke said after his club was held to three hits in Wednesday's 4-1 loss. "I don't know how to put it any other way than just the mistakes we miss, they are not missing."
Philadelphia (40-51) is at the bottom of the East but has won the first three games of this set after losing nine of 10.
"Winning is the cure-all of cure-alls," said Jonathan Papelbon, who has saved all three games.
The Brewers are 4 for 22 with runners in scoring position in the series and have hit .195 overall in their last nine games while averaging 2.7 runs. Jean Segura is in a 4-for-37 funk, Khris Davis is in a 1-for-14 slump and All-Star Carlos Gomez hasn't scored or driven in a run in six straight games.
"Don't panic, every good team does this so it's just a matter of making sure we're getting good at-bats," first baseman Lyle Overbay said.
Maybe getting Ryan Braun back can provide a spark. He's missed the last two games and three of four with back trouble, though Roenicke was hopeful Braun would return Thursday.
Garza (6-5, 3.78 ERA) can't be blamed for the club's woes. He's averaged 1.21 walks per nine innings over his last five outings, compared to 3.52 through his first 13. He tied a season high with nine strikeouts Saturday in his first complete game since Aug. 3.
"He's thrown the ball really well for the fourth, fifth game in a row," Roenicke said. "I'm hoping that this being the best of them will get him back in a groove where he reels off a couple of months of great ballgames."
Garza's had plenty against the Phillies, going 2-1 with a 1.77 ERA in six starts.
Philadelphia's regular 2-3-4 hitters - Jimmy Rollins, Chase Utley and Ryan Howard - are 4 for 37 against him. Howard has gone 0 for 10 with five strikeouts versus Garza, and he enters in a 4-for-44 slump and homerless in 20 straight games.
Rollins, though, ended an 0-for-20 drought with a two-run homer in the sixth inning Wednesday. Utley hit his second homer of the series, during which he's 6 for 11 with six RBIs.
The Phillies will start David Buchanan (4-5, 4.82), who has allowed no more than three runs in five consecutive outings but has lost his last two.
The rookie right-hander gave up three runs in six innings of a 3-2 loss at Pittsburgh on Saturday. However, the only walk he surrendered was intentional after issuing nine unintentional walks in his previous two games.