Gross hit a grand slam to cap a five-run seventh inning and the Brewers beat the Arizona Diamondbacks 7-4 on Tuesday night, keeping Milwaukee tied with the Chicago Cubs for first place in the division.
"We were due to win a few and due to win a few on the road," Gross said.
Gross was hitting .202 when he was optioned to Triple-A Nashville on July 21, but is hitting .400 (8-for-20) with three homers and eight RBI since his return August 15.
"He needed some at-bats," said Brewers manager Ned Yost. "It's hard when you're getting three and four at-bats a week. So we sent him to Nashville so he could get four at-bats a day, thinking it would sharpen him up - which it did."
Chris Young hit his team-leading 25th home run for the Diamondbacks, who have lost three straight for the first time since July 15-17. Two of those losses have come against the Brewers, who are 5-1 against Arizona this year.
"I sense my offense is getting hot," Yost said. "My offense is starting to get it together and score runs and my pitching staff is too. It was just a matter of time."
First-place Arizona remained 3½ games ahead of San Diego in the NL West. The Diamondbacks, who had won nine straight series, have lost only two series since the All-Star break -- both to Milwaukee.
"As well as we were playing, I didn't think we were going to win every series for the rest of the year. That's a little unrealistic," said Arizona outfielder Eric Byrnes, who was 3-for-5 with a double, a stolen base and an RBI. "I think the thing is to come back tomorrow and win that game. But the Brewers, they've had our number this year."
Byrnes' run-scoring single and Conor Jackson's RBI double cut it to 7-4 with two outs in the ninth before Francisco Cordero struck out Stephen Drew with a runner on second for his 37th save in 43 chances.
Arizona's Mark Reynolds struck out in his first two at-bats against Dave Bush to match the record of nine consecutive strikeouts by a non-pitcher, set five times before, most recently by Kansas City's Bo Jackson in 1988.
Bush hit Reynolds with a pitch in the sixth, ending the streak.
Arizona tied the score at 2 in the sixth inning when Young led off with his homer just over the left-field fence, Byrnes hit a one-out double and Drew lined a double to right.
"We had an opportunity to take the lead," said Arizona manager Bob Melvin. "When they get out of it, sometimes that swings the momentum into the other dugout a little bit and they took advantage of it."
The Brewers answered in the seventh against Livan Hernandez (9-8). Bill Hall doubled to start the inning and scored on Johnny Estrada's double, making it 3-2. Hardy added his third hit before Hernandez was lifted for Tony Pena.
Pena retired pinch-hitter Joe Dillon but walked Weeks. Gross followed with his seventh homer of the season and second career slam into the pool area behind the right-field fence to give the Brewers a five-run lead.
"Grand slams are nice," Gross said. "They change ballgames pretty quick."
Milwaukee's rally helped Dave Bush (10-9) earn his first win since a July 31 relief appearance against the New York Mets. Bush allowed two runs and six hits over six innings with one walk and six strikeouts.
"He spent every bit of reserve he had to hold that score at two," Yost said. "To see the boys come back and reward him with a win by getting him some runs was awesome."
Hernandez, who won four of his previous five starts, was charged with five runs and seven hits in six-plus innings.
- Milwaukee was 5-for-9 with runners in scoring position.
- Bush has three wins in his last eight appearances, two against Arizona.
- Milwaukee has seven grand slams this season.
- Reynolds was 0-for-4 with four strikeouts against two Milwaukee pitchers Monday, and had struck out in his last three at-bats Saturday and Sunday in Atlanta.
- Brewers manager Ned Yost said he will wait until at least Thursday before deciding whether right-hander Ben Sheets will return to the rotation this weekend in San Francisco. Sheets, who has been on the disabled list since July 15 with torn tissue in his right index finger, cut short an outing in a simulated game Monday because of a blister on that finger.