The slugger's 25th home run of the season barely reached the right-field seats, good enough for the most crucial hit in a win that snapped a five-game losing skid. The victory also kept the Astros in prime position for a Wild Card berth -- 1 1/2 ahead of the Angels for the second spot -- and within 2 1/2 games of Texas for the division lead.
"It woke everybody up," manager A.J. Hinch said. "It put a lot of belief that we remember how to win games like this."
It didn't always look like Gattis would be the hero. In fact, Gattis was in line to be the goat after a first-inning baserunning gaffe kept Gray afloat.
The Astros, already up 3-0, had runners on first and second with one out. Gray was at 38 pitches, and the A's bullpen was already warming up. Another hit, perhaps another run might have ended Gray's night for good.
Instead, Luis Valbuena lofted a fly ball that didn't reach the warning track in right field, and Gattis tagged up and aimed for second. His nine triples not withstanding, Gattis was still nowhere near quick enough to reach second.
"It was a mistake. I've never done that before, that particular play," Gattis said. "It's something to learn from. Should only take one time to know I can't reach there, so I don't want to repeat that."
The out extended Gray, who didn't allow another run until being pulled with one out in the sixth.
Meanwhile, the A's surged to a three-run advantage, eventually whittled to a 6-5 advantage when Gattis stepped up with two on and two out in the seventh. An opposite-field looper from Gattis later and the Astros were suddenly back in business after a dismal week.
"[The emotions] were just pretty overwhelming," Hinch said. "That's the biggest hit in the biggest moment."
Make no mistake, Gattis knew he had some atoning to do, be it through his single off Gray in the fourth or the seventh-inning shot.
"I was just glad to be up in that spot," Gattis said. "Had the baserunning error earlier and got a chance to make up for it.
"This was clearly a big game for us. We bounced back in a big way."
Chris Abshire is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.