Cueto allowed three hits over eight innings, including two solo homers, and singled home a run on Saturday night, leading the Cincinnati Reds to a 6-2 victory over the Milwaukee Brewers.
The Reds have won two of the first three in the series, leaving Milwaukee with a six-game lead in the NL Central.
Cueto (3-2) gave up homers by Aramis Ramirez and Mark Reynolds and an infield single by Jean Segura. He walked one and struck out 10. The right-hander has allowed only three runs in his last 38 innings.
"He's always good," Brewers manager Ron Roenicke said. "He's always really good.
"We knew were were going to have a tough time when we faced him. You hoped to get a great pitching performance to match him and see what happened."
Gallardo (2-1) was good but not great, failing to produce a quality start for the first time this season. Cincinnati had nine singles in Gallardo's six innings, including Cueto's RBI hit in the sixth inning for a 4-2 lead.
"They put the ball on the ground," Gallardo said. "There's nothing I can do after that. It's frustrating when you make a good pitch and something happens. Cueto was a fastball away and he threw the bat out and made contact."
Gallardo gave up season highs in hits and runs. He had only one strikeout, his lowest total since July 30.
"(Gallardo) wasn't quite on today," Roenicke said. "He didn't throw any curveballs for strikes. We need to get that pitch back. You have to have an off-speed pitch that they have to worry about."
Ryan Ludwick singled home a run, and Brayan Pena drove in two more with a single in a three-run fourth inning. Todd Frazier doubled home a run as the Reds pulled away against the bullpen.
The game matched two of the NL's stingiest pitchers. Cueto got the better of it, leaving his league-leading ERA at 1.31.
Cueto is the first Red to throw at least seven innings in each of his first seven starts in a season since Bucky Walters in 1944. He's the first Red to throw at least eight innings in four straight starts since Jose Rijo in 1990.
One curiosity with Cueto: He has given up six homers, accounting for seven of the eight runs he has allowed this season. He gave up two homers in a game for the first time this season.
Reds leadoff hitter Billy Hamilton was out of the lineup for the second consecutive game because of sprained knuckles on his left hand.
The Brewers' offense has struggled and been in flux for the past week because of slumps and injuries. It took a significant hit on Saturday when Ryan Braun went on the disabled list with a strained right oblique.
Braun had missed the last six games with the injury. He's eligible to return on May 12. Outfielder Logan Schafer, who had been disabled by a strained right hamstring injury, was activated in Braun's spot.
Ramirez and Segura, the shortstop, missed time in the past week because of injuries. Ramirez, bothered by a bad elbow, was in an 0-for-28 slump that matched the longest of his career when he led off the second inning with a homer.
The Reds broke a 12-inning scoreless streak by piling up singles in the fourth. They loaded the bases on hits by Brandon Phillips and Jay Bruce, and Frazier was hit by a pitch. Ludwick singled home one run, and Pena drove in two more.
NOTES: Alfred Simon (4-1) faces Milwaukee's Kyle Lohse (4-1) in the final game of the series on Sunday. ... The Reds activated OF/INF Skip Schumaker before the game. Schumaker separated his left shoulder while diving for a ball in the outfield on March 21. OF Roger Bernadina was designated for assignment. ... Closer Aroldis Chapman pitched one inning for Class A Dayton at Lake County on Saturday, throwing 16 pitches. He's expected to continue his rehab assignment with Triple-A Louisville and could be activated within a week. Chapman was hit on the forehead by a line drive on March 19 and had surgery to insert a plate.