BALTIMORE -- The 104th and final pitch thrown by Astros starter Framber Valdez on Saturday afternoon appeared to have done the job. Orioles rookie outfielder Colton Cowser rolled over a sinker with two outs and hit a slow grounder. The ball came off the bat at 72.1 mph and was hit right at first baseman Jon Singleton.

Singleton initially took a step back as he fielded the three-hop grounder and immediately found himself in a footrace with Cowser, who runs well despite his 6-foot-2 frame. Just as Singleton stuck out his left foot, Cowser dove headfirst to beat Singleton to the base.

“It’s very frustrating,” Singleton said. “Sometimes one play can make or break a whole game.”

That loaded the bases for relief pitcher Tayler Scott, whose first pitch to rookie pinch-hitter Jackson Holliday -- who was in an 0-for-20 slump -- was ripped into the right-center-field gap for a three-run double that sent the Orioles to their second consecutive comeback win over the Astros, 3-2, at Camden Yards.

“I thought I got out of the inning there when the ball was hit,” said Valdez, who called it a routine play. “It was one of those things you can’t expect in baseball.”

Singleton thought he had more time and was taken by surprise on Cowser's dive.

“There’s two options: run through or hopefully try to flip it,” he said. “I didn’t expect him to dive at first. It is what it is.”

Houston’s inability to complete the play at first base in the sixth underscored the team’s struggles finding consistent play at the position. The Astros jettisoned veteran first baseman José Abreu in June in the middle of a three-year, $58.5 million deal, and first base has been a revolving door since.

Seven different players have started games at first base this season, and catcher Victor Caratini and rookie Joey Loperfido -- who was dealt to Toronto in July -- have also had time there. The Astros have considered playing third baseman Alex Bregman at first base while he deals with some elbow inflammation.

“That’s where we’re at right now,” Astros manager Joe Espada said. “I’m not going to get into specifics. We have guys, and I like the guys we have. We have to put guys in a position where they can succeed and make plays and get some offense out of those guys. We’ll continue to navigate those waters, and we’ll get it done.”

Espada said both Singleton and Valdez should have shown more urgency on the Cowser grounder. Valdez jogged to first and wasn’t an option for Singleton to flip the ball to.

“There’s no way when a ball is hit that close to the [base], that soft, the guy should beat the defense to the spot,” Espada said. “That’s just from my end. I just got to look at it closely and see.”

All three runs were charged to Valdez, who was inches away from throwing six scoreless innings. The Astros had won the 10 previous games Valdez had started, having not suffered a loss with the lefty on the mound since June 18.

“Obviously, we lost the game there, but I thought it was one of those outings I did a really good job, as well,” Valdez said. “Baseball is like that. When you think you have the game in your hands, it takes it away from you.”

Cowser, a left-handed hitter, ran fast out of the box and was down the first-base line at 29.7 feet per second.

"Singleton is a big guy,” Cowser said. “I didn’t really feel like going head on with him. I may have slowed down a little bit, but I felt like I could maybe sneak my hand in there. It’s kind of an unconventional thing to do, you're not really taught to do that. But just instincts took over."

The Astros have lost four of their past five games on the heels of winning 11 of 12 games, but they maintained their 4 1/2-game lead atop the American League West after the Mariners lost to the Giants. It was the second day in a row the Orioles beat the Astros on a bases-loaded hit. Anthony Santander slugged a go-ahead grand slam off Bryan Abreu in the eighth inning Friday.

“It looks like you kind of got things lined up well, got a couple of runs and are looking forward to giving the ball to our back end of our bullpen,” Espada said. “They just put some good ABs together, and things didn’t go our way.”