"Against a team we've struggled against some, it was good," A's manager Bob Melvin said. "I can't remember us sweeping anybody for a while. It feels good."
The A's are two games over .500 and hitting nearly 40 points better since the break. Matsui has plenty to do with that.
Matsui is hitting .343 (62 for 181) since the All-Star break. He hit .209 in the first part of the season. The three doubles tied a single-game Oakland record.
"It seems like he's always contributing," Melvin said. "Any young player can learn from him. He means a lot to this team."
Matsui was a little more modest.
"I wish I would have helped the team score more runs earlier in the season," Matsui said through an interpreter. "That's one thing I am disappointed about. He struck me out with a pitch inside in my first at-bat, but I felt pretty good afterward."
"It felt like I was pitching out of a big situation every inning," Cahill said. "I was able to make pitches when I needed to make them."
Blake Beavan (3-5) pitched five innings for Seattle and was charged with four runs and seven hits. The rookie right-hander is 0-3 with a 6.44 ERA in his last five starts.
"I threw the ball OK," Beavan said. "The first three innings I thought there were some good pitches but I didn't get the calls. I keep trying to keep the same mindset and not try to be too fine."
Seattle center fielder Franklin Gutierrez departed in the eighth inning with a severe left oblique strain. He grabbed his left side after a swing and miss and needed help off the field.
"He's been swinging the bat much better the last month or so," Mariners manager Eric Wedge said. "There's a pretty good chance he's done for the year. If he is done, he can take the past month with him into the offseason and to spring training."
The Mariners also lost outfielder Casper Wells, who left with a bruised left elbow after getting hit by a pitch in the second inning. Wedge said he will be re-evaluated on Monday.
Cahill's previous victory came on July 27 against Tampa Bay. He's allowed 28 runs in 38 2/3 innings for a 6.52 ERA since holding the Rays scoreless over 7 1/3 innings.
Kurt Suzuki's RBI single in the second gave the A's the early edge. DeJesus added a sacrifice fly in the third and a run-scoring single in the fifth. Allen also drove in a run in the fifth.
Suzuki hit an RBI single in the fifth for the Mariners' first run. Ackley hit his sixth homer with two outs in the seventh.
The Athletics responded with four runs in the bottom half of the seventh. Sweeney hit a two-run triple and Willingham had a sacrifice fly.
A's OF Coco Crisp missed the game to recover from fouling a ball off his foot on Saturday. ... Mariners RHP Dan Cortes is expected to make a rehab appearance with Triple-A Tacoma on Monday, then join the team at home later in the week. ... A's OF Michael Taylor was not in the starting lineup two days after Melvin said he would be. "I put my foot in my mouth there," Melvin said. "He'll start against some left-handers. He'll get a chance to play. He's not here to sit." ... Mariners INF Brendan Ryan, who was on the disabled list in August with a left shoulder injury, got the day off. ... Oakland raised $63,200 on A's Breast Cancer Awareness Day. ... LHP Anthony Vasquez starts for the Mariners when they open a series in Anaheim against the Los Angeles Angels on Monday. It will be his third major league start and his second against the Angels. ... RHP Rich Harden starts Monday's game for the A's against the Kansas City Royals. He has 64 strikeouts since the All-Star Break, fifth in the AL. He is 2-0 in five home starts.