After the game, Keuchel was asked to describe the first inning.
"Very interesting," he said. "I couldn't dwell on it. I thought there was a couple of plays that were close. That pretty much just sums up our season. I couldn't dwell on it, though, because I would have been in a world of hurt. I got out of it and gave us a chance to win."
Keuchel, who threw seven scoreless innings in his previous start Sunday against the White Sox, held Seattle to three runs, four hits and two walks in seven innings while striking out eight batters. He has a 1.93 ERA in his last two starts, but is 0-1 in that span.
The lefty retired 12 in a row at one stretch and faced the minimum of 18 hitters from the second inning through the seventh.
"He had a good stretch," Mariners shortstop Brad Miller said. "Obviously, we were glad we jumped out early on him because that ended up being the difference, but you have to keep going out there."
The Astros' offense struggled for the fourth game in a row and is batting .176 (22-for-125) in that span, including 0-for-18 with runners in scoring position. They were 0-for-8 with runners in scoring position on Saturday.
"Just not being able to get the big it," Astros manager Bo Porter said. "We've had opportunities and had men in scoring position, and the big hit is just avoiding us at this point."
Keuchel started the game by giving up a bloop single into left field by Miller on a 3-2 pitch. With one out, Kyle Seager singled off the glove of second baseman Jake Elmore, and one out later, Kendrys Morales hit a grounder that shortstop Marwin Gonzalez reached out to grab, but his throw to second base to start a potential double play sailed wide to allow a run to score.
Keuchel walked the next two hitters, including Nick Franklin with the bases loaded to score a run, before Dustin Ackley grounded out to score Morales and give the Mariners a 3-0 lead.
"It's the big leagues and those innings are going to happen," Keuchel said. "I thought Marwin made a good play. The throw was a little bit off. Who knows? We make that double play it could be 1-0 us. The fact of the matter is, I let three runs score in the first and that was the difference."
The only baserunners Keuchel allowed after that were on a hit by pitch in the fifth and a leadoff single to Seager in the sixth. Astros 31-year-old rookie catcher Cody Clark erased both baserunners, throwing out Miller trying to steal and Seager trying to advance on a pitch in the dirt.
"Nothing surprises me anymore with Cody," Keuchel said of his fellow Arkansas alum. "He's a rock back there. He's a big league catcher."
The Astros put the first two runners on base in the second before Saunders got Barnes to hit into a double play. Saunders walked the next two hitters to load the bases for Clark, who grounded into a fielder's choice to end the inning.
"Their first two starters this series, we hadn't seen them this year and you have to make adjustments in-game," Barnes said. "You have to take your first at-bat and go off that. They've all three pitched good games and weren't leaving very many balls over the plate."
The only run the Astros scored came in the fourth and courtesy of an error by Franklin, who dropped a throw from catcher Humberto Quintero when they had Elmore caught trying to steal second base. Barnes raced home from third to cut the lead to 3-1.
"Elmore waited until the ball went to home plate [from the pitcher] and he should have been first move," Porter said. "He delayed going and he should have went immediately. That's why he almost ended up being out. They catch the ball, it's either a rundown or he's out."
Saunders, who was 2-1 with a 5.94 ERA in three starts against the Astros previously this year, allowed one unearned run and six hits in 5 1/3 innings. A diving stop by Miller to rob Clark ended the fourth and stranded a runner at second.
"That was huge," Saunders said. "I was trying to keep the ball on the ground most of the night. They've got some guys that can hurt you, so I tried to use the sinker and changeup as well as I could to try to keep them off balance. For him to make that play and pick us up there was huge."