A strong start by Zack Greinke Greinke, some huge strikeouts by rookie fireballer Enoli Paredes and a clutch hit by Alex Bregman weren’t enough to save the Astros from their second consecutive walk-off loss Friday night.

After Bregman put Houston ahead with an RBI single in the top of the 13th, the A’s rallied for two runs in the bottom of the inning off Cy Sneed. Marcus Semien’s bases-loaded single into the gap brought home Robbie Grossman for a 3-2 win at the Coliseum.

• Box score

“They sting a lot because we’re battling and scuffling to win every game and we’re losing late like this and it really hurts badly,” Astros manager Dusty Baker said. “You’ve got to keep on fighting. It’s like Groundhog Day. It’s happening over and over, especially in the late innings.”

Here are three takeaways from the loss, which sent the Astros under .500 (6-7) for the first time this year and 3 1 /2 games behind the A’s in the American League West:

1. Paredes shows his stuff
By now, everyone knows how the Astros have been relying on so many young arms this season because of a rash of injuries. For the most part, they’ve done a solid job. Andre Scrubb threw a scoreless eighth Friday, and another rookie, Humberto Castellanos, threw a scoreless 12th, but it was Paredes who stole the show and perhaps showed a glimpse of how he can be relied upon in big situations going forward.

Throwing heat from the get-go, the rookie right-hander struck out five batters while working the 10th and 11th innings. He stranded the automatic runner at third each inning. His four-seam fastball explodes on hitters at 99 mph. In the 11th, he got Mark Canha on three pitches and whiffed Khris Davis and Austin Allen on high fastballs out of the zone. He threw 23 of his 30 pitches for strikes and averaged 95.9 mph on his fastball.

“I’m just focusing on throwing the ball and doing my best to help the team win,” said Paredes, the Astros’ 14th-ranked prospect, per MLB Pipeline. “I didn’t think too much. So every day I’m on the mound, when I get the opportunity to go into a game, I want to do my best.”

Semien, who struck out on a 98.6 mph heater in the 10th, said Paredes has one of the best fastballs the team has seen this year.

“We had never seen him,” he said. “Now we know. I’m sure we’ll face him again this year and know what to expect. At this level, you know all you have to do is hit the ball to the outfield, but it’s really not that easy, especially against that guy. Good job by him.”

2. Clutch hits elude Astros
Getting the automatic runner home in extra innings has been difficult for the Astros, who fell to 1-3 in extra innings, including 0-2 in 13-inning games. They were 0-for-9 with runners in scoring position in extra innings Friday before Bregman’s double scored Garrett Stubbs.

The Astros were 3-for-17 with runners in scoring position in the game and left 13 men on base. They have scored the automatic runner in only four of 11 extra innings this year. On Friday, they tried to bunt for the first time in extra innings but stranded Myles Straw at third in the 10th.

“We had a lot of chances, a lot of chances,” Baker said. “Boy, sometimes you can score runs at will, but right now hits are tough to come by.”

3. Greinke was exceptional
There was an argument for keeping Greinke in the game past the six scoreless innings he threw, especially with the state of Houston’s banged-up and inexperienced bullpen. The bottom line is Baker thought Greinke had enough after stressful innings in the fifth and sixth.

In the fifth, Greinke got a 6-4-3 double play with the bases loaded to end the inning, and in the sixth pitched around a leadoff triple by Ramón Laureano -- the result of Straw slipping in center field -- by striking out Matt Olson and Matt Chapman and getting Canha to pop up.

“After I struck out the first batter, when I got two strikes on [Chapman], I knew the strikeout would be big,” Greinke said. “I tried a little harder on that one. And then the last batter it was just normal, trying to get someone out.”

• Greinke hangs with cutouts during his start

Greinke didn’t panic and got creative in the sixth. He did everything he wanted to do and executed flawlessly with his pitch usage. Greinke was pulled after 84 pitches in the seventh for Josh James, who gave up a game-tying homer to Grossman.

“He had two stressful innings back to back where he got out of trouble,” Baker said. “So we thought that was enough. It’s only his third start. That was the decision. We discussed it and he wanted to go longer, but we thought that was enough.”

When asked if he could have gone longer, Greinke said: “I wasn’t really tired. It’s still early in the year, but the last two outings I’ve felt really good the whole game.”