"I think that's the guy we're used to seeing," A's manager Bob Melvin said of Cahill. "He was working his pitches on both sides of the plate, backdoor sinkers in the middle, he's got a lot of weapons and you saw all of them tonight."
Blake Beavan (5-6) was roughed up in five innings. The righty gave up seven runs on eight hits while fanning two and walking four.
Oakland wasted no time taking the lead in its first at-bat when Coco Crisp worked a one-out walk and Hideki Matsui singled before Willingham brought everybody home with his three-run home run blast to left, his 29th home run of the season.
"Blake was a little bit out of sync early on, a little choppy," Mariners manager Eric Wedge said. "We wanted to give him time to work his way out of trouble early. He didn't have the fastball command we're used to seeing him have."
The A's added two more runs in the third courtesy of an RBI single into right by Sizemore and Kurt Suzuki followed with a sacrifice fly to expand the lead to 5-0.
Matsui singled to right to open the A's fifth before Sizemore crushed a 1-2 hanging breaking ball deep to left off Beavan with two outs, ballooning the A's lead to 7-0.
Dustin Ackley worked a leadoff walk and Smoak roped a single into right two batters later in the home seventh, but the Mariners were unable to solve Cahill, as he got Miguel Olivo swinging and induced a soft lineout from Seager to end the inning.
Beavan is 1-2 in three career starts against the A's...With a 10-8 lead in the season series between the teams, the Mariners have locked up the season series win...Seattle is 21-35 against the American League West, while the A's are 25-31 against their own division...Beavan had his 24 2/3 consecutive inning walkless streak snapped...A's infielder Jemile Weeks extended his hitting streak to eight games.