Gallardo will also be seeking his fourth consecutive victory Friday night with another successful outing against the Philadelphia Phillies.
The Brewers' run of success at Miller Park looked like it might be in jeopardy in Thursday's series opener. They trailed by a run in the eighth inning, before Hart delivered a grand slam to lift Milwaukee to a 7-4 win - its seventh in a row at home.
Ryan Braun added a pair of solo homers after going 6 for 42 (.143) with 14 strikeouts over his previous 10 games, and Aramis Ramirez also went deep.
Kevin Frandsen had a three-run double for Philadelphia, though it ultimately went for naught.
"You got to give Frandsen some credit, getting that bases-clearing double to give us the lead," said Phillies starting pitcher Cliff Lee, who struck out 12 in 7 2-3 innings and didn't get a decision. "That was huge by him. We just weren't able to keep the lead."
Gallardo (11-8, 3.78 ERA) will try to help the Brewers (53-64) win eight in a row at home for the first time since July 10-Aug. 1, 2011.
The right-hander is 3-0 with a 2.08 ERA over his last three starts. He pitched a season-high 7 2-3 innings in Sunday's 5-3 victory at Houston, giving up three runs while striking out eight.
"I felt pretty good (Sunday). I was able to command all of my pitches," Gallardo said. "I'm just trying to go back out there and get back in that same rhythm I was in before."
Gallardo is 2-0 with a 1.98 ERA in two career starts against the Phillies (54-64), including a 3-2 home win last Sept. 11 in which he struck out 12 and allowed two runs and three hits over seven innings.
Gallardo will have a great opportunity to defeat Philadelphia again if counterpart Vance Worley's struggles continue. The right-hander is 1-2 with a 5.60 ERA over his last five outings and has given up four runs in each of his last two.
After failing to make it out of the fourth inning of a loss to Atlanta on Aug. 6, Worley (6-7, 3.97) pitched into the sixth Sunday against St. Louis but did not get a decision in an 8-7 win.
He started opposite Gallardo during the Sept. 11 game at Miller Park, giving up three runs over 6 2-3 innings and striking out seven. He also started the Phillies' 10-inning, 7-6 home win over the Brewers on July 25, allowing three runs and scattering 10 hits over 5 1-3 innings.