ST. LOUIS -- The Astros got three consecutive quality starts over the weekend in Los Angeles from rookie starting pitchers J.P. France, Ronel Blanco and Hunter Brown, setting up ace lefty Framber Valdez -- baseball’s king of the quality start -- to keep the good run of pitching going Tuesday night at Busch Stadium.

Valdez, other than a leadoff homer to Paul DeJong in the third inning, was up to the challenge through three innings before the Cardinals changed their approach and started hitting the ball to right field and took advantage of some Houston miscues to beat Valdez and the Astros, 4-2, in the series opener.

Valdez, who last year set the Major League single-season record with 25 consecutive quality starts, had delivered a quality start -- at least six innings pitched and three or fewer earned runs -- in 12 of his first 15 starts this year, including a shutout against Oakland. He gave up four runs, eight hits and three walks in six innings in his first career start against St. Louis.

“It definitely looked like they made some adjustments [after the first three innings],” Valdez said. “I was falling behind a lot of the hitters, wasn’t making some of my pitches and just given the situations, a pitcher falls behind in some of the counts, and the hitters can get a little more comfortable. They took advantage of the moments.”

The Astros led 2-0 after a Statcast-projected 438-foot homer by catcher Martín Maldonado to lead off the third and didn’t score again against Cardinals starter Jordan Montgomery or two relievers the rest of the way.

Two runs can be enough to back Valdez when he’s on his game -- the Astros won, 2-0, in his May 21 shutout of the A’s -- but that wasn’t the case Tuesday.

DeJong’s homer was the first Valdez has allowed on a curveball this season, and Maldonado said Valdez should have bounced the pitch. Instead, it hung over the middle of the plate.

“I felt like all the mistakes were hit that we threw today,” Maldonado said.

DeJong wasn’t done inflicting damage against Valdez. In the fourth, he hit a long sacrifice fly to right field on a sinker with the bases loaded that tied the game. Valdez had to feel fortunate considering the ball left DeJong’s bat at 101.7 mph.

“DeJong hurt us,” Astros manager Dusty Baker said. “It looked like he almost hit that ball out to right field. Their pitcher kept the ball down, got some double plays when he needed it, kept his pitch count down. Usually, that’s Framber’s game. He was on his game tonight. He was throwing below the zone with his breaking ball and changeup and sinker, and then he’d throw above the zone with two strikes. They had a game plan against us, too, and they executed it.”

Things got really messy for Valdez in the fifth, starting with a one-out walk to Paul Goldschmidt on a 3-2 curveball. Nolan Arenado hit a double that one-hopped off the right-field wall, scoring Goldschmidt. No one backed up an errant relay throw from second baseman Mauricio Dubón, which allowed Arenado to take third. He scored on a wild pitch.

“He got a couple of balls up in the zone that he usually doesn’t get up to good hitters like Arenado -- his double,” Baker said. “It was a big run when nobody backed up the throw, and the guy went to third and they scored on a wild pitch. We’ve got to stress the little things because that’s what’s costing us runs, especially when you’re not scoring a bunch of runs.”

The Astros, who had scored 25 runs in their previous four games, had a huge chance when they loaded the bases with two outs in the seventh. The Cardinals brought in right-hander reliever Giovanny Gallegos; Baker countered with lefty pinch-hitter Bligh Madris, who batted for Maldonado and flied out to left field.

“Madris had a good at-bat and just got up under the ball,” Baker said. “We just came up short.”