Soriano's shot to center field ended a 12-inning scoreless streak over 14 appearances by Perez, who came in with a 0.94 ERA in 31 relief appearances. Perez threw a low 95-mph fastball on the 1-2 count, but said it wasn't the right location against the veteran Soriano.
"I was trying to go higher, because I know he's a good low-ball hitter. I just missed the pitch," Perez said. "Normally you keep the ball down to be more successful. But everybody knows Soriano is a very good low-ball hitter, and he golfed the ball and that happens. Every time there's going to be a winner and a loser and that was me today."
Perez struck out Soriano in the ninth inning on Friday when Seattle won, 5-4, in 10 innings, but this time the Cubs designated hitter won the battle.
"He threw me first two pitches fastball, and the third one, he threw me a breaking ball," Soriano said. "When I saw the breaking ball, it gave me more confidence at home plate. I wanted to try to swing at a strike and make good contact, and he threw me a fastball in the middle and I had a good swing."
The Mariners hit the halfway mark of the season with a 35-46 record, one game better than last year's midseason pace. The Cubs are 34-45 going into Sunday's finale of the three-game Interleague series.
The game ended in unusual fashion, with Mariners pitcher Joe Saunders pinch-hitting for Perez with two out in the bottom of the 11th, after Seattle lost its designated hitter position when Dustin Ackley sprained his thumb in the top of the ninth.
The converted second baseman was playing just his second game in center field since being recalled and handled four fly balls flawlessly before rolling over on his glove hand trying to get to Soriano's low line drive. Wedge said Ackley would likely miss a few days.
Since Jason Bay had pinch-run for DH Kendrys Morales in the eighth, Bay went in to play the outfield after Ackley's injury, but that eliminated the DH position, and Seattle's pitchers inherited the No. 8 spot in the order where Ackley had been hitting.
Backup catcher Henry Blanco pinch-hit for Charlie Furbush in that spot in the bottom of the ninth, but manager Eric Wedge was out of position players by the time it came around again in the 11th, so he sent up Saunders -- a career .136 hitter -- and he popped out to center to end the game.
"When I knew we'd lost the DH, I had an inkling that I'd maybe get an at-bat," said Saunders. "Hopefully it doesn't come to that, but you just try to do your job. In that case, I was just trying to get on base."
The Mariners rallied from a 3-2 deficit in the bottom of the ninth to tie the game on an RBI single by Endy Chavez. But they couldn't pull out the win and are now 4-7 in extra-inning games.
Veteran right-hander Aaron Harang turned in a solid start with eight innings of three-run ball and wound up with a no-decision after the Mariners late rally.
Harang has been largely feast or famine this season. He's had two complete-game shutouts, but otherwise had yet to pitch beyond six innings in any of his 10 other starts since being acquired in an early-season trade with the Rockies.
The 35-year-old put up eight strong innings against the Cubs, allowing just five hits and three runs with no walks and one strikeout on 105 pitches. The no-decision left him with a 5.08 ERA.
"I felt really good and was making pitches when I needed to," Harang said. "My changeup was really good today. That was nice to have. It was really keeping them off balance, because my slider wasn't there early. But as the game went on, I felt I was starting to get a better grasp for it, and it showed up late and I was able to make some key pitches."
Justin Smoak blasted a solo home run to kick off a two-run second inning for Seattle, his soaring blast into the right-field seats coming on a first-pitch fastball from Jeff Samardzija. It was Smoak's sixth homer of the season, with three of those coming in his last eight starts since returning from the disabled list with a strained oblique.
"I was sitting dead-red first pitch and got the fastball and put a pretty good swing on it," Smoak said. "I'm feeling better. It's just a matter of getting back in that rhythm and timing with everything coming off the DL. I'm feeling better and better every time out."
Smoak went 2-for-5 and had a chance to drive in the tying run in the eighth, but Raul Ibanez was thrown out at the plate trying to score from second on Smoak's single to left fielder Brian Bogusevic.
"It's baseball," said Smoak. "The guy made a great play. He's got to charge it and make a perfect throw to get him. Tip your cap to them right there."
Ackley had an RBI single to left in the second, snapping an 0-for-23 stretch sandwiched around a stint in Triple-A Tacoma.