Encarnacion hit a towering grand slam to cap a six-run rally with two outs in the third inning, and the Cincinnati Reds started their longest road trip this season by roughing up Gallardo in a 7-6 win Monday night.
"I just tried to look for something in the strike zone -- hopefully a fastball because he got behind the other hitters," Encarnacion said. "I hit it in the perfect spot."
Jay Bruce also hit his first homer of the year as the Reds overcame a four-run deficit with a scoring binge to begin an 11-day, 10-game trip that includes series against NL Central rivals Houston and Chicago.
Milwaukee has lost three straight despite building a 5-1 lead in the first two innings off Reds starter Edinson Volquez, who labored again allowing six runs off seven hits and four walks.
But Gallardo (1-1) gave it back and the Reds bullpen held on with four scoreless innings, capped by Francisco Cordero's second save this season.
While Volquez (1-1) struggled, Gallardo had an ugly 40-pitch third inning that began innocuously with two outs.
Brandon Phillips walked to load the bases, Bruce was hit by a pitch to score another run and Encarnacion hit a belt-high fastball deep over the Brewers bullpen for his third career grand slam to give the Reds a 7-5 lead.
"After that, the damage was done," said Gallardo, who retired the final seven batters he faced. "I blew a four-run lead. I was pretty upset about that."
Gallardo got that early advantage off Prince Fielder's fielder's choice in the first and four runs in the second on Jason Kendall's RBI single and Corey Hart's three-run homer that left Volquez kicking the mound.
The Reds' right-hander regained his composure, pitching through a no-out, bases-loaded jam in the fourth after giving up consecutive singles and hitting Rickie Weeks with a pitch that caught the Brewers' second baseman on his collar bone and jaw as he squared up to bunt and sent him sprawling face down.
"Everybody on the bench was amazed that he was wanting to stay in and he was fine," Brewers manager Ken Macha said. "I got out there, I said, 'Where'd it hit you?' and he said in the jaw."
Weeks stayed in the game but never left first as Volquez retired the Brewers' best three hitters -- Hart, Ryan Braun and Fielder -- to end the threat.
"It was a battle," Volquez said. "I was confident that I could get those guys out."
Bruce's solo homer got the Reds on the board in the second, while Brewers shortstop J.J. Hardy hit a homer leading off the fifth that made it 7-6. Volquez got through that inning, leaving him in line for the win despite his ERA rising to 9.64 in 9 1/3 innings over two starts.
"Edinson has a way of getting into trouble, but he has a way of getting out of it," Reds manager Dusty Baker said. "They could've broken that game wide open."
Instead, the Reds bullpen of Jared Burton, Arthur Rhodes, David Weathers and Cordero held on with Milwaukee stranding runners in scoring position the final three innings. Weathers got the biggest out by forcing Hardy to fly out to center field with the bases loaded and two outs in the eighth.
"That's the great thing about having veteran pitchers," Weathers said. "Nobody ever panics."
Hart has homered in consecutive games. ... Kendall's RBI single snapped an 0-for-15 start this season. ... Brewers closer Trevor Hoffman (oblique) threw off flat ground on Monday before the game. Macha said Hoffman's next rehab step will be throwing off a mound on Wednesday. Hoffman last threw off the mound on March 13. ... Macha said he'll speak Tuesday with Brewers SP Jeff Suppan, who is 0-2 with a 12.91 ERA to start this season while making a team-high $12.5 million this season. "I'm happy for him. He's making $12.5 million," Macha said. "Instead of looking at how much money he's making, we've got to look at how we're going to get this guy pitching like he has in the past."