ST. LOUIS -- If the stakes were not so high, and the calendar so short, this might have been one of those hard-fought, crisply-played losses the Brewers could have felt good about.But given their current circumstances, Sunday's 10-inning, 5-4 loss to the Cardinals was a killer. If the Brewers are to continue their climb into the National League Wild Card race, they can ill afford any losses at all, even ones as spirited as Sunday's. Outfielder Norichika Aoki hit a tying, two-run home run off Cardinals closer Jason Motte with two outs and two strikes against him in the ninth inning, but the Cardinals came back to win anyway, dashing the Brewers' hopes of a three-game sweep "I'm OK with the three games we just played -- we played great," Milwaukee manager Ron Roenicke said. "We lose today, shoot, that's a great team we're playing, and we played a really good game today. They came through with a big hit." That big hit came from Allen Craig, who lined a Kameron Loe pitch to right field with two outs in the 10th and a runner at second base. The runner, Matt Carpenter, had grounded a single through the hole between first and second base and advanced to scoring position when pinch-hitter Adron Chambers struck out on a wild pitch that got past catcher Jonathan Lucroy. Carpenter made a wide turn at third and executed a perfect slide around Lucroy, who was just up the baseline to receive Aoki's strong throw. The Cardinals scored their fifth walk-off win at Busch Stadium this season. "It's huge," Carpenter said. "We needed this game badly. To do it in that kind of fashion, hopefully that will get us on some kind of roll. Hopefully we can take this momentum and get on a good little stretch here." Said Cardinals manager Mike Matheny, whose club begins a West Coast swing on Monday in San Diego: "That would have been a long, long flight if we didn't pull that off." The Brewers lost for only the fifth time in 20 games and fell back to six games behind the Cardinals for the second NL Wild Card berth. Two other teams stand in the way of the Brewers, who will return from their 4-3 road trip to Miami and St. Louis to host the Braves starting Monday. "We're still right there," said Brewers first baseman Corey Hart Hart exited the game in the fifth inning with a left ankle injury, and left fielder Ryan Braun was out an inning later after he tweaked a lingering right wrist issue. By then, the Brewers were already in a hole. Right-hander Shaun Marcum surrendered a pair of first-inning home runs in an outing reminiscent of his two forgettable starts against the Cardinals in last year's National League Championship Series. In Game 2 of that series, a 12-3 Brewers loss, Marcum surrendered a two-run homer to Albert Pujols in the first inning and fell into a 5-0 hole by the fourth. In Game 6, the 12-6 loss that ended the Brewers' season, Marcum surrendered four first-inning runs including a three-run homer to David Freese. The stakes were not quite as high on Sunday, but were still significant. "Marcum, the first inning [his] command was all over the place," Roenicke said. "After that, he settled down." In the first, John Jay smacked a leadoff single and scored two batters later when Matt Holliday hammered a full-count curveball that was low in the strike zone for a two-run home run to left field. Two batters after that, Carlos Beltran hit a hanging first-pitch curveball for another home run and a 3-0 Cardinals lead. It was Beltran's first home run since Aug. 10. In four starts since returning from a two-month stint on the disabled list with a right elbow injury, Marcum has pitched five, four, 5 2/3 and five innings. He settled in Sunday after allowing a pair of doubles in the second, retiring 10 of the final 12 men he faced while allowing no more runs, but the damage was done -- four Cardinals runs on eight hits over five innings in all. Cardinals starter Joe Kelly mostly stymied the Brewers over six innings, allowing two runs on five well-placed hits. The only sharp hit was Aoki's double leading off the game; he was stranded at second base. Aoki struck again in the ninth against Motte. With Jean Segura on base after the last of his career-best three hits, Aoki lined a 99 mph fastball down the right field line for a home run that bounced off the top of the wall and into the seats. He briefly stopped between first and second base to ensure that first base umpire Jim Wolf knew he'd touched the bag. When Aoki resumed his trot around the bases, he pumped his right fist in the air. "I wasn't really thinking anything, I was just swinging at whatever pitch comes, so I was excited coming around first base," he said through translator Kosuke Inaji. "It was a line drive, too, so I wasn't sure. The right-field corner kind of comes in a little, too, so I guess that helped me. I was just excited in that situation." So were his teammates. Braun and Hart were among the Brewers watching on television in the clubhouse. "It doesn't get any bigger than that," Braun said. "When things like that happen, that's when you know things are going your way. That could have just as easily hit the top of the wall [and bounced back into play] and not tied it." Up next for the Brewers is another key series against the Wild Card-leading Braves. Braun's and Hart's status will be determined Monday afternoon. "We're playing good baseball," Braun said. "Hopefully we continue to do that over the next 22 [games]."