Seattle got on the board in the third inning on a walk to Ryan Langerhans and a run-scoring double just inside the left-field line by Ichiro Suzuki -- his 199th hit of the season.
Ichiro had three other chances for his 200th hit but struck out, flied out and grounded out.
Both teams sat around for more than four hours waiting for the rain to stop and the opener of a rain-precipitated doubleheader to begin.
The opener, originally scheduled to start at 10:35 a.m. PT, was pushed back twice before the first pitch finally was thrown at 3:07 p.m. PT.
"That shouldn't have been a factor, and it wasn't," Fister said. "That didn't play into going out there and performing and today I struggled in keeping the ball in the right location. The keys to me are keeping the ball down and having good location.
"When the ball gets up, it's just easier to hit."
Fister needed to pitch the same kind of game Rangers right-hander Tommy Hunter threw against the Mariners. Seattle was held to six hits and showed more impatience than usual.
"It was about offense and not getting anything started," manager Don Wakamatsu said. "I thought Tommy Hunter threw a nice game, but we talk about having a solid game plan. I thought we had a good plan against [Kevin] Millwood yesterday and were over-aggressive against Tommy."
Hunter became the seventh starter this season to toss a complete game against the Mariners, compared to three pitched by Seattle pitchers.
Hunter already was ahead by three runs when the Mariners scored a run in the third inning.
"[Hunter] kept us off-balance and threw a good game, but we need to get his pitch count up and not let him complete that game," Wakmatsu said.
The Mariners were retired in order in the first inning, beginning with Ichiro's routine grounder to second base, and again in the second as Hunter had only one ball leave the infield.
But the bottom of the first inning was not at all routine for Fister (2-2). After striking out Julio Borbon, the right-hander surrendered an infield single and double, putting runners on second and third bases.
An infield out scored the game's first run and one swing in the second inning by Chris Davis scored the second run, which came via a home run onto the grass in center field.
"Fister was really the opposite [of Hunter]," Wakamatsu said. "He got his pitch count up, left a few too many over the zone and gave up quite a few hits."
Fister, who entered the game with 2.79 ERA, surrendered 10 hits in all over 4 2/3 innings.
But the defense let him down on a couple of occasions.
"In defense of Fister, there was a double-play ball that should have been turned, and another ground ball probably cost him another inning of work, pitch-wise," Wakamatsu said.
Two-time Gold Glove-winning third baseman Adrian Beltre committed an error to extend the third inning and shortstop Jack Wilson's low throw of the back end of a double play in the fourth did the same thing, only this time a run scored.