Thanks in large part to Alonso and Juan Francisco, the Reds were up for the challenge.
Francisco hit a three-run homer and drove in five runs and Alonso had a two-run homer and scored three runs as the Reds beat St. Louis 11-8 on Friday night to end the Cardinals' four-game winning streak.
Todd Frazier added a pinch hit, solo home run for Cincinnati.
Reliever Marc Rzepczynski (0-1) started the seventh for the Cardinals in a 6-6 game and got Joey Votto to ground out to lead off the inning. But Bruce singled to left and Alonso followed with his fourth homer to make it 8-6.
"It was an important home run, but Todd's was, too, and so was Francisco's," Alonso said. "They all came at good times.
"That (home runs) is the last thing obviously we're thinking about against Carpenter. We got out with a W and that's good."
With the heart of the Cardinals' lineup lurking in the bottom of the ninth, Cincinnati manager Dusty Baker was glad to have the extra runs.
Furcal and David Freese each had a solo home run and an RBI single for St. Louis, and Jon Jay was 2 for 3 with two runs scored. Holliday added a solo homer in the ninth off Cincinnati reliever Francisco Cordero.
Carpenter had one bad inning, the second, when Cincinnati sent 10 men to the plate and scored five times. After Alonso reached on a double and Drew Stubbs on a fielder's choice to start the inning, Francisco drove them both home with a double. Phillips, Renteria and Bruce all drove in runs with two-out hits to make it 5-0.
"Obviously, a big game for us and the five runs in the second wasn't what I was looking for," Carpenter said. "I didn't pitch well enough to give our guys a chance. Offensively, we did a nice job. I couldn't get out of the second inning."
St. Louis manager Tony La Russa thought with better luck, Carpenter could have gotten out of the inning with a lot less damage.
"They had three balls that were mis-hit," La Russa said. "That's a tough five-spot to hang on him. He deserved better. They should have got something, but not five."
Alonso said the Reds wanted to take advantage of Carpenter when they could.
"Carpenter is really good," Alonso said. "When you face top-notch guys you got to grind and you got to battle and we did that."
Speaking of grinding, the Cardinals began pecking away at Cueto, getting two runs back in the bottom of the second on an RBI single by Freese and Yadier Molina's fielder's choice. St. Louis plated a single run in the third on Berkman's RBI single, and tied it in the fifth on Furcal's homer and a double play by Holliday that scored Jay to tie it 5-5.
Frazier hit a solo shot off Carpenter with two out in the sixth to give the Reds the lead again, but Freese tied it with a solo homer off Arredondo leading off the bottom half.
Furcal has homered in three straight games. ... The Reds are looking to win their first three-game series in St. Louis since June 5-7, 2006. Cincinnati is 0-12-1 in 13 series since. ... Carpenter has allowed 21 of his 85 earned runs in the second inning. ... Votto, who went 2 for 5, leads the NL with a .358 road average. ... Freese also grounded into a double play, giving the Cardinals a majors-leading 147. ... Homer Bailey (7-6) starts for Cincinnati on Saturday against Cardinals left-hander Jaime Garcia (10-7).