But the unearned run came because he made the error himself when he was unable to pick up Craig Biggio's bunt to the right side of the infield in the seventh inning.
"I've got to make that play," Marquis said later.
One big out and a whole lot of extracurricular activity later, what turned out to be the winning run scored on a sacrifice fly.
Not long after that pivotal play on the field, Marquis, hailed as perhaps the best overall athlete on the Cardinals' pitching staff, was unable to get a bunt down after the Cardinals' leadoff man had reached base in the eighth, popping up to the catcher.
But it was the bunt he didn't pick up with his glove the inning before that wound up really turning into a big play in the Astros' favor.
After Marquis allowed a leadoff walk to pinch-hitter Orlando Palmeiro to start the bottom of the seventh, Biggio laid down a firm bunt that headed to the area between the mound and first base. Marquis attacked the ball, but couldn't get it into his glove as Biggio sprinted to first.
"I didn't know whether Albert [Pujols, the Cardinals' first baseman] was charging in or not," Marquis explained. "I was just trying to pick up the ball and try and beat Biggio to the bag. I just didn't pick it up on the way."
Three batters later, the Astros had gone ahead, and Cardinals manager Tony La Russa had been ejected from the game. The go-ahead run scored on Morgan Ensberg's sacrifice fly to center, with pinch-runner Willy Taveras sliding home.
One batter before Ensberg, Marquis' pitches became central to the disputes with home-plate umpire Phil Cuzzi that led to La Russa's ejection. Marquis walked Lance Berkman on four close pitches, and La Russa's complaints about the calls from the dugout were answered with Cuzzi tossing him from the game.
"All day in the bullpen, a couple of guys were talking about how consistent he'd been behind the plate," Marquis said. "Then I came in and everything changed. But you've still got to make pitches."
Marquis had success against the Astros during the regular season, going 4-0 with a 3.22 ERA in five starts, including a complete-game victory Sept. 4 at Houston, and a relief appearance. But Suppan got the starting nod for Game 4, and he delivered another strong big-game performance, allowing just one run on three hits in five innings before Marquis was summoned from the bullpen.
Unlike Marquis, Suppan hadn't pitched against the Astros all season.
"[It] wasn't anything we tried to avoid. It's just the way it worked," La Russa said. "I mean, there's a lot of things that are maddening about this game, but that's one of them. The job that [Suppan] did, the way our club responded, I mean, everything, we did so many good things. But it starts with Jeff, to pitch that well with that extended amount of time between starts, I mean, it was really extra special. And Jason came in and he did a really good job, as well."
La Russa declined to discuss the disputes with Cuzzi over the strike zone following the game, and Marquis wasn't looking to point the finger at the umpire, either.
"I thought I threw some good pitches," Marquis said. "That being said, I can't blame the umpires. I got myself into some holes where I was down 3-0 and 2-0. I'm not pitching against the umpires. I'm pitching against the Astros. I'm not blaming anybody but myself."