SEATTLE -- Mike Zunino has been in the big leagues just a little more than two weeks, though any nerves he was feeling walking to the plate with the bases loaded and one out in the 10th inning certainly didn't show.
Zunino might have looked like a veteran as he worked the at-bat, but that doesn't mean he wasn't feeling the pressure until he saw the ball make it through the infield.
"It was a giant sigh of relief," Zunino said. "Anything you can do to help the team win, that's what I'm all about. I would have taken a sac fly, I would have taken anything in that situation."
Michael Saunders and Raul Ibanez led off the 10th with back-to-back walks before Blake Parker (0-1) was relieved by Shawn Camp. Jason Bay advanced both runners with a sacrifice bunt, and Justin Smoak was intentionally walked to load the bases with one out to bring up Zunino.
The rookie catcher was called up to majors on June 11 and was playing in his 11th game. He had a total of one RBI in 37 at-bats before walking to the batter's box in the 10th inning.
After the winning run scored, Zunino's teammates mobbed him at first base in celebration.
"Oh, man. A couple of rib shots and some slaps on the back, but it's definitely worth it at that point," Zunino said. "Any situation like that, I'll be able to take it."
Bay hit his ninth home run and Nick Franklin had two doubles among his three hits for the Mariners, who had lost two in a row.
Cubs starter Travis Wood left in position for his first win in five starts after allowing two runs on three hits and striking out six in 6 1/3 innings, but Chicago's bullpen failed, leaving Wood winless since May 30.
"The outcome is the outcome," Wood said. "They played a good game, so did we. We battled, they battled, battled and battled and ended up coming back and winning the game."
The Cubs had a 4-2 lead going into the eighth with James Russell on the mound when Seattle tied the game on Kendrys Morales' RBI double and Ibanez's run-scoring triple on a line drive that got past sliding left fielder Brian Bogusevic and rolled to the wall.
Mariners starter Hisashi Iwakuma pitched eight innings, with four runs and six hits allowed. He struck out five. It was the fourth time this season Iwakuma has completed eight innings, and all four times he has come away with a no decision.
"Besides the two home runs I gave up -- they were to the fat part of the plate -- overall I thought it was good," Iwakuma said through a translator.
The Cubs led 2-1 going into the seventh and added to their lead with a pair of home runs, both coming on the first pitch. Soriano led off with a drive just inside the left field foul pole, his eighth. With two outs Novarro also hit his eighth homer to right-center.
The Cubs took advantage of a throwing error by second baseman Franklin in the second inning to take a 2-0 lead. Soriano led off the inning with a single, and with one out Ryan Sweeney hit a hard grounder down the first-base line that got into the deep right-field corner for a triple. Soriano scored and second baseman Franklin's relay throw home got past catcher Zunino, allowing Sweeney to score on the error and giving the Cubs a 2-0 lead.
The Mariners didn't get a hit until the fourth inning when Franklin led off with a double and didn't score until Bay homered to lead off the fifth. All nine of Bay's home runs this season have been solo shots.
Seattle scored again in the seventh when Brad Miller -- making his major league debut after being called up from Triple-A Tacoma before the game -- drove in Bay with a fielder's choice.
Miller was 0-for-3 with a walk, RBI and stolen base in the game.
"It was so much fun, just getting out there and running around and playing was pretty sweet," Miller said.
Miller was the eighth player to make his MLB debut with Seattle this season. ... Seattle optioned INF Carlos Triunfel to Tacoma and designated INF Alex Liddi for assignment. ... The Mariners started Dustin Ackley at CF for the first time. ... The Cubs have homered in a season-high eight straight games.