Jackson threw a gem, allowing five hits in 7 2/3 innings as the Tigers won, 2-0. He struck out six and walked just one, his final batter, earning his first victory since coming over in an offseason trade. He is now 3-0 with an 0.40 ERA against Seattle in three career starts, allowing 14 hits and just one run in 22 2/3 innings.
Bobby Seay took over for him in the eighth and stuck out Ichiro Suzuki. Fernando Rodney worked the ninth to pick up his third save.
The Tigers scored their runs with two outs in the sixth. With Miguel Cabrera on second and Gerald Laird on first, Brandon Inge lofted a shallow single to right. That scored Cabrera, and Laird came home when Ichiro's throw sailed into the stands.
"I just felt weak," Jackson said. "I'm not sure if it's a slight case of what's going around, but I was not fully energized."
Leyland, who had to send right-hander Adam Everett back to the hotel with the flu, said Jackson was well enough to start "but it didn't get going to around the first or second inning."
In the first, after running to back up third on a one-out double by Endy Chavez, Jackson said he nearly threw up.
"I thought there was a chance," he said. "But you don't think about it. As a professional, you don't really go out and make excuses. There are a lot of people playing sick and hurt. I'm not one to complain.
"Just go out and try to get the job done."
He did. He induced Ken Griffey Jr. to pop up to first, then Adrian Beltre bounced out to third.
"You get a double, then have two guys who can put the ball way back in the bleachers, you can't think about it," he said. "You just have to go out and try to attack them."
He continued to attack, retiring the next nine batters in the row and getting some help from his defense.
In the fourth, second baseman Placido Polanco made a nifty backhanded stop -- with the umpire moving in front of him -- on a hard one-hopper by Adrian Beltre.
"That was a rocket," Leyland said. "Great play. He turned it into a double play."
Then, in the fifth with Jose Lopez on third and one out, Yuniesky Betancourt hit a fly ball to center field. Curtis Granderson caught it in stride and threw out Lopez at the plate for another inning-ending double play.
"I probably showed some emotion on that play," Jackson said. "Great throw. That changed the game. That's a run right there if that throw's not perfect like it was."
Jackson allowed a couple more singles over the next 2 2/3 innings before Leyland felt he had given all he could. He brought in Seay to pitch to Ichiro.
"He one of those guys who can finish a game," Leyland said of Jackson. "He's a warrior, man, I've really been impressed with him.
"He's quite a competitor. He had an electric slider, too."
Mariners catcher Rob Johnson, who managed a couple of singles off Jackson, added, "He's got great stuff. He mixes his fastball at 91 and then 96 and he's got a filthy slider, so he keeps you off balance.
"He's a very good pitcher."
The Tigers mounted a threat in the seventh. Granderson drew a walk from Roy Corcoran. After Polanco sacrifice bunted Granderson to second, Magglio Ordonez singled to left, sending Granderson to third. Cabrera then flied out to left. Granderson tagged and tried to score but was thrown out by Endy Chavez.
He was one of three thrown out at the plate by outfielders.
After the game, Jackson said he felt ill, but it didn't appear to be getting worse.
"The sickness is in back of my mind," he added. "Until the game was over, I just worried about going out and pounding the strike zone and help us get a chance to get a win."