HOUSTON — Detroit Tigers left-hander Tarik Skubal, who has been the best pitcher in the American League this season, hadn't allowed a hit since his first pitch of the game.

And then, in the sixth inning, Skubal gave up back-to-back hits as part of four hits allowed in a four-run frame.

The Tigers couldn't recover from Skubal's downfall in the sixth — his first messy inning in a long time — in a 4-0 loss to the Houston Astros in Friday's opener of a three-game series at Minute Maid Park. In the sixth, the Astros' aggressive approach against Skubal finally paid off with hits.

It's just the third time in 14 starts that Skubal has allowed more than two earned runs. His ERA increased from 1.92 to 2.20.

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The reason the Tigers (33-36) didn't help their ace? It wasn't surprising, but the offense didn't do anything against right-hander Hunter Brown, the Detroit native and Wayne State product who fired seven scoreless innings with nine strikeouts.

Skubal surrendered four runs on six hits and one walk with two strikeouts across 6⅓ innings, throwing 84 pitches. He was pulled with one out in the sixth inning, thus avoiding a fourth matchup with Jose Altuve.

That's because Altuve — who drilled a leadoff double on the first pitch in the first inning — got the party started for the Astros in the sixth inning with his second double on a first-pitch slider at the bottom of the strike zone.

The Astros then took a 1-0 lead when Alex Bregman hit a second-pitch sinker for a triple to right-center field. He scored easily, making it 2-0, on Yordan Alvarez drilled a first-pitch sinker for a sacrifice fly to center field.

With two outs, Yainer Diaz worked deeper into the count to keep the inning alive with a single. Then, Mauricio Dubón hammered a first-pitch changeup — located middle-down at the bottom rail of the strike zone — for a two-run home run to left field.

The homer from Dubón put the Astros ahead, 4-0.

Skubal faced 27 batters.

Thirteen of those batters put one of the first two pitches in play, resulting in five of the six hits against Skubal, and three of those five hits occurred in the sixth inning.

Skubal, who threw 21 pitches in two-strike counts, recorded his two strikeouts in the first inning, but the Astros didn't strike out against the swing-and-miss artist in the second, third, fourth, fifth, sixth or seventh innings because of their aggressive approach.

Ryan Kreidler's mistake

A Little League-caliber mistake hurt the Tigers in the third inning.

Ryan Kreidler didn't touch first base on a double (that should've been a triple, anyway). The Tigers should've had a runner on third base with no outs in the third, but after the Astros challenged, there was one out with the bases empty.

Brown fired seven scoreless innings on 96 pitches against the Tigers in his best start this season, working around five hits. He didn't allow a walk and struck out nine batters.

The mix of his sinker, cutter and four-seam fastball confused the Tigers. Brown added the sinker to his pitch mix at the beginning of May and has thrived since then.

Robbing Riley Greene

Astros center fielder Jake Meyers robbed Riley Greene of a solo home run in the top of the ninth inning.

The Tigers finished with five hits — all singles — and zero walks.

Contact Evan Petzold at epetzold@freepress.com or follow him @EvanPetzold.

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This article originally appeared on Detroit Free Press: Detroit Tigers stumped by Wayne State's Hunter Brown in loss to Astros