Gallardo (6-3) was impressive but not quite as sharp as Lewis, surrendering four runs on six hits in six innings, while striking out 10 batters and walking four.
Fielder, meanwhile, broke out of a recent skid with his blasts, accounting for all of the Brewers' offensive output. Prodigious as Fielder's blasts were -- the second was hit to dead-center field -- his two RBIs were matched by the Rangers hurler.
"Sometimes it's just that person's day," Fielder said of Lewis. "So there's nothing you can do about it."
Early on, it looked like it would be Gallardo's day. He struck out the side in the first inning but produced just two more clean innings -- the third and the fifth -- and he struggled with his efficiency on the mound.
"I thought Yo threw all right," Macha said. "They had a couple big at-bats while he was pitching."
Gallardo's day came down to those two at-bats, one in the fourth and another in the sixth.
Two batters after Gallardo surrendered a leadoff double to Rangers third baseman Michael Young, Josh Hamilton smacked a two-run homer to right field on a 2-2 changeup, giving the Rangers a 2-1 lead.
After retiring the Rangers in order during the fifth inning, Gallardo once again struggled in the sixth, giving up a leadoff single to Vladimir Guerrero and a double to Hamilton. After consecutive strikeouts and an intentional walk, Lewis stepped to the plate with two on and two out.
Lewis worked the count to 2-2, fouling off four pitches, then ripped a single down the left-field line, scoring Guerrero and Hamilton and making it 4-1 in the Rangers' favor.
"When I got to two strikes, I basically told myself to spread out, react to the fastball and put the ball in play," Lewis said. "I just tried to put a good swing on it. I know he's been dealing the last six or seven starts."
Gallardo, who has been known to swing the bat pretty well himself, was also among those impressed by Lewis' at-bat in the sixth.
"He fouled off some good pitches," Gallardo said. "That last curveball, I was trying to go away, and it kind of came down and in. He hit it down the line, and I was kind of surprised, just that he was able to keep it fair.
"He had some pretty good swings in his first two at-bats. He definitely knew what he was doing. It just shocked me that he fouled off all those pitches."
Lewis (6-4) also tossed eight strong innings, allowing two runs on three hits while striking out 10 and walking just one.
"Lewis had real good control of his slider; he pretty much threw that for a strike whenever he wanted to," Brewers manager Ken Macha said. "He cut the ball, he sunk it with the fastball, pretty much had us off balance."
With the loss, the Brewers dropped two of three games against the Rangers and finished a 3-3 homestand that started when they took two of three games against the Cubs.
"It's very frustrating," said Fielder. "But that's just how it is sometimes, especially in baseball. There's nothing you can do about it. ... All you can do is keep playing."
Jordan Schelling is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.