Garcia, the Mariners' promising 27-year-old right-hander, got hit hard and lost for the first time since May 21 in a 7-3 defeat to Texas at the Ballpark in Arlington.
All seven runs were charged to Garcia (9-7), who had won six decisions in a row coming into the game and was recently named the American League's June pitcher of the month.
In the early innings, Seattle (54-31) moved ahead and spotted their hot pitcher an early 3-0 lead.
But Texas answered in grand fashion, tagging Garcia for five runs on five hits in the fourth inning. The big blow was a three-run blast to centerfield by Juan Gonzalez, who connected on a fastball left over the plate. Alex Rodriguez and Todd Greene each added RBI base hits as well.
Texas (34-51) added two runs in the seventh on sacrifice flies by Michael Young and Rafael Palmeiro to cap the scoring.
R.A. Dickey (4-3) picked up the win for the Rangers. Dickey came in and pitched three scoreless innings after starter, Victor Santos, was pulled when it took him 95 pitches to get through four innings.
Dickey struck out two and didn't walk a batter.