HOUSTON — One of the biggest reasons the Astros have opened up a season-high four-game lead atop the American League West — two months after they were 10 games behind the second-place Mariners — is the resurgence of right-hander Hunter Brown, who’s pitched as well as anyone in baseball for more than two months.

With the rotation decimated by injuries, Brown has picked up the slack, and then some. His impressive stretch continued as he threw seven innings of one-run ball in Saturday’s 6-1 win over the White Sox at Minute Maid Park, Houston’s ninth victory in its last 10 games.

Brown improved to 9-2 with a 2.33 ERA in 12 starts since June 11, giving him a Major League-leading 9 wins in that span. He’s thrown at least six innings in 14 of 16 starts since May 22 and is about as automatic as the retractable roof at Minute Maid Park being closed in the summer.

“Obviously, when you’re having success it feels good,” he said. “In that one game maybe if you can squeeze out another inning and help the bullpen for tomorrow’s game or anything like that, it definitely feels good, and you can definitely build off it and try to keep it rolling.”

Brown (11-7) allowed a two-out run in the first inning and then held the White Sox off the board the rest of the way for his team-leading 14th quality start. It marked the seventh time in his career he’s pitched seven innings, which is a career high.

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“Yeah, he’s got good stuff,” White Sox designated hitter Gavin Sheets said. “Four-pitch guy, has electric stuff. I think he mixed well when he threw strikes with all of his pitches. That’s the biggest thing for him, when he’s in the zone with all of his pitches, he’s really tough to hit. I thought he threw the ball well.”

Manager Joe Espada said Brown’s development has included being able to brush things off when they don’t go well, as he did in the first inning when the White Sox rallied after two outs and took the lead on an RBI single by Sheets.

“It’s just confidence,” Espada said. “He knows that he is a guy we’re going to rely on and he’s a guy we want to go deep into games. He knows he’s got ace stuff. It just takes time for a young pitcher to believe that and work through some of that. That’s part of being young. You want to get everyone out and you want everyone to make plays behind you. I get it. I want that also, but it takes time. Hunter is starting to figure out, ‘If I give up a soft single or something happens behind me, I can get somebody out.’”

White Sox starter Chris Flexen retired the first seven Astros hitters before No. 14 prospect Shay Whitcomb — called up from Triple-A Sugar Land on Friday and starting at third base Saturday — ripped a two-out double to right field in the third inning. That was the first of five consecutive hits for the Astros, who got a two-run single by Jose Altuve and an RBI single by Yordan Alvarez to take a 3-1 lead.

Whitcomb went 2-for-3 with a walk and a run scored in his debut and became the 13th player in Astros history to hit a double in his first career game. He is also the 11th player in club history to record an extra-base hit of any type in his first plate appearance.

“It’s a dream come true,” Whitcomb said. “I’ve looked forward to this day for a long time. The whole time I was just overwhelmed with joy.”

Espada was so impressed with Whitcomb’s swing and plate discipline, he said he’ll be in the starting lineup for Sunday’s finale.

“He looked calm, poised and I’m just really happy for him,” he said. “I’ve seen him come to big league camp for the last couple of years and he’s one of those quiet kids that goes about his business. I asked him to play everywhere on the field [in the spring]. He goes, ‘All right, let’s go.’ To see those guys get to the big leagues, it’s awesome. And then to perform the way he did, it makes it even better.”