Starting pitcher George Kirby also was scratched because of illness.
"[Kirby] was sick most of the night and just felt terrible today, and when he came in, we just felt best that we move on and not pitch him in the ballgame tonight," Servais said. "George loves to be out there. He's an awesome competitor, but we've got to do the right thing. He was under the weather."
Then, first baseman Ty France left after two innings with a bruised left thumb sustained on a pickoff.
"Stuff happens," Servais said. "We play so many games. We've been on such a hot streak where everything kind of has gone our way. So [there's] going to be a little bump in the road, a little adversity."
The loss to the A's ended the Mariners' two-day stay alone atop the American League West. Seattle had won 12 of its previous 13 games, turning a 7 1/2-game deficit into a one-game lead over Texas. The Rangers won 2-1 at the New York Mets, matching the Mariners at 75-57. Houston is a percentage point back at 76-58.
The Associated Press contributed to this report.