It's the second time in the club's 53-year history the Astros have hit two grand slams in one game. Jimmy Wynn and Dennis Menke both hit slams to beat the Mets on July 30, 1969, accomplishing the feat in the same inning. A team doubling up on grand slams in one game hasn't happened often -- just 70 times, with 13 of those happening when one player hit a pair of slams. The MLB record is three in one game, set by the Yankees, against the A's, on Aug. 25, 2011.
"They whacked the ball all over the place today," Twins manager Ron Gardenhire said. "We got back in a little bit, and then they killed it at the end."
The slams capped the biggest day of the season offensively for the Astros, who scored their most runs in more than a year. Houston hit four home runs -- with Dexter Fowler and George Springer adding solo shots -- which traveled a total of 1,574 feet.
"It's been fun," said Singleton, who homered to right off All-Star closer Glen Perkins. "We like playing off of each other, and that's definitely a bonus. One person does well and it carries over. It's contagious."
The Astros have won 11 of their last 15 games and are 17-10 since May 11, with a resurgent offense leading the turnaround. Houston is hitting .263 as a team in its last 27 games after hitting .220 in the first 37 games.
A big reason has been the addition of Springer, who came up in late April, took off in May and clubbed his 12th homer of the season Sunday. Singleton, another highly-touted prospect who was playing in his sixth game, has added more thump to the lineup.
"Any time you have several guys in your lineup who can change the game with one swing, it puts more strain on the opposing pitchers because they feel like, 'I can't make a mistake here,'" Astros manager Bo Porter said. "That can drain on a staff."
The Astros had 24 baserunners on 13 hits, eight walks and three hit batters. Twins starter Samuel Deduno (2-4) suffered the brunt of the damage, giving up five runs on five walks and three hits in three-plus innings.
"They're pretty good," Deduno said. "It just frustrates me because I didn't make any good pitches. I couldn't throw anything for a strike. If I make my pitch and throw strikes, and with the movement on my fastball, I think I would've pitched pretty good. But today I didn't have anything."
The Astros built a 5-0 lead by scoring three times in the fourth, getting bases-loaded singles from Jonathan Villar and Fowler and a sacrifice fly by Jose Altuve, who has hit safely in 28 of his last 30 games. He added a pair of stolen bases to give him 23 for the season.
The Twins clawed back into the game against Houston starter Collin McHugh, who was bothered by a blister on his right hand. He lasted only 4 1/3 innings and allowed three runs while walking five batters.
"When you walk guys like that, you're giving guys free bases and your pitch count is going through the roof," said McHugh, who threw 101 pitches.
The Astros led, 5-3, in the seventh when Carter rocketed an opposite-field grand slam to right off Brian Duensing to make it 9-3. It was the Astros' first grand slam since last September, but it wasn't their last one of the day.
"I've had lots of chances, and I was thinking about it when I got up to the plate today and thought, 'Maybe one could happen this time,'" Carter said. "It worked out finally for me this time."
Porter has kept the struggling slugger in the lineup because of his ability to change the game with one swing, and his faith was rewarded.
"It's power to all fields," Porter said. "I love the way he attacked the ball today. Even his first at-bat, the line drive to left field, that ball was attacked and hit hard. As long as he continues to attack the baseball, he is a weapon any time he steps in the batter's box."
In the ninth, Singleton (2-for-6) turned on a 1-1 pitch from Perkins and launched it high over the right-field wall. It was the first time since 1988 the Twins have allowed two grand slams in a game.
"To be honest, I was looking to hit something hard anywhere," Singleton said. "He threw something over the plate I could handle, and I hit it hard."
Darin Downs (1-0) picked up the win for the Astros after finishing the game with 2 2/3 innings of scoreless relief, but this day was about the offense.
"Oh boy," Porter said. "It was good to see the offense break out today, and we needed every last one of them, especially when Collin had to come out of the game early. Give the Twins credit. They didn't go away. They kept battling and kept battling, and it was good to see our offense break out."