The A's haven't had much of a chance to catch their breath lately after playing four games in three days across three time zones.
Perhaps all that travel - from Arlington to Seattle to Denver - caught up with them Tuesday.
The A's went 0-for-9 with runners in scoring position and committed their first error since Sept. 8 in a 3-1 loss to the Colorado Rockies at Coors Field.
The A's scored their only run in the top of the second inning as a Tony Kemp sacrifice fly to center field brought home Jake Lamb.
Otherwise, they were stymied by Rockies starter Antonio Senzatela, who allowed just six hits and handed A's starter Sean Manaea his first loss since July 31.
The A's (30-19) also left five runners on base as their magic number to clinch a playoff spot remained at five, as the Houston Astros beat the Texas Rangers 4-1. The A's still have a 5 1/2 game over lead the Astros, and have 11 games left to play.
The A's played Texas four times in three days from Friday to Sunday. They then flew to Seattle, where, amid unhealthy air quality, they played the Mariners twice on Monday.
The A's flew to Denver after Monday's doubleheader but did not arrive at the Mile High City until 2 a.m. local time.
"(Monday) didn't help, but we need an off day," A's manager Bob Melvin said.
The A's fell behind by one in the fifth inning as Manaea allowed a two-run homer to Elias Diaz.