Pineiro's complete-game shutout improved his record to 5-4 and lowered his ERA to 3.86. It was just the second complete game of his four-year career.
Twins' starter, Kyle Lohse, didn't fair much worse. Though he received the hard-luck loss, the 24-year-old Native American went eight strong innings.
He fell to 4-4 on the year.
The Mariners (35-18) connected for eight of their 12 hits off of Lohse, but could only manage to push three runs across the plate against the right-hander.
They pushed two more across in the fourth, using three consecutive singles by Edgar Martinez, John Olerud and Winn to score the first run of the inning. Olerud later scored on a sacrifice fly, making it 3-0.
That was more than enough for Pineiro, who had the Twins off-balance all game by mixing speeds and hitting locations. By spotting his offspeed pitches, he was able to blow away the Minnesota (31-22) lineup with his low-90's fastball.
Pineiro struck out everyone in the Twins' lineup except catcher A.J. Pierzynski. Four batters - Luis Rivas, Dustin Mohr, Corey Koskie, and Matt LeCroy - fanned twice.
Seattle tacked on its final three runs in the ninth off of Twins' reliever J.C. Romero. The middle reliever walked two and gave up four hits, the loudest being a two-run homer by centerfielder Mike Cameron. It was Cameron's sixth long-ball fo the season.
Mabry Hurtin': The Mariners placed outfielder John Mabry on the disabled list prior to Friday's game with a rare shoulder injury. Mabry, who figures to be out for a month, suffered the injury while diving for a ball Wednesday in Kansas City. He'll be replaced on the roster by 40-year-old catcher Pat Borders, who's torn up Triple-A pitching for two months at Tacoma.