BOSTON -- Seattle's Dustin Ackley had never faced Jon Lester before Monday night and afterward said that the Boston Red Sox left-hander's cutter looked identical to his fastball.
Ackley wasn't the only Mariner who couldn't figure out Lester.
Lester scattered eight hits without walking a batter in his second complete game of the season to lead the Red Sox to their fourth straight win, 6-1 over Seattle.
"He's got some great pitches. His curveball's a great pitch, too," said Ackley, who went 1 for 4 with a single. "He gets ahead with that on guys early, and when he's able to use the cutter, it's a great pitch for him. When you have a pitch like that, you're going to miss barrels a lot."
Swing and miss the Mariners did.
Seattle didn't manage a hit off Lester (2-3) until Ichiro Suzuki singled with two outs in the fourth inning, and they mustered merely six hits -- all singles -- through eight innings. Lester struck out six, including Alex Liddi to cap his first nine-inning complete game since June 27, 2010. He also tossed an eight-inning complete game earlier this season in a loss at Toronto.
Lester required 119 pitches to finish off his eighth career complete game, surrendering the lone run in the ninth when Suzuki singled, moved to third on a double by Justin Smoak and scored on Kyle Seager's groundout.
"I've seen him pretty good, unfortunately. But he was good tonight, too," Mariners manager Eric Wedge said. "He's a smart kid. As he works his way through the lineup the second and third times, he does a nice job mixing-and-matching and he did a lot of that tonight."
Daniel Nava and Kelly Shoppach homered for Boston.
David Ortiz and Adrian Gonzalez added consecutive RBI doubles for the Red Sox, who won their fourth straight at home. Boston is on its longest home winning streak since capturing nine straight last July.
The Red Sox opened just 4-11 at Fenway Park.
The Mariners, on the second stop of a four-city, 11-game trip, have dropped four of six. Seattle entered the day with the AL's second-worst batting average at .235.
Suzuki and Smoak each had two hits for the Mariners.
Jason Vargas (4-3) had his worst start of the season, allowing five runs and seven hits in six innings. He had allowed two runs or fewer in six of his eight starts this year.
Lester retired the first 11 batters before Suzuki reached on an infield hit when the ball caromed off the pitcher's glove. Third baseman Will Middlebrooks had little time to make a throw when he finally recovered the ball.
Leading 2-0, the Red Sox increased their lead to 5-0 on the homers by Nava and Shoppach. Nava hit his second career home run into the first row of seats above the Green Monster after Cody Ross singled leading off the fourth. One out later, Shoppach belted one over the Monster seats, completely out of Fenway, for his first of the season.
Nava's only other homer was a grand slam on the first pitch he saw in the big leagues, making him just the second player in major league history to accomplish the feat. Kevin Kouzmanoff was the other, doing it with Cleveland in 2006.
Marlon's Byrd's sacrifice fly made it 6-0 in the eighth.
Boston had grabbed a 2-0 lead in the first on doubles on consecutive pitches to Ortiz and Gonzalez.
Boston's Dustin Pedroia went 0 for 4, snapping his 14-game hitting streak.
NOTES: Nava, who spent all of 2011 at Triple-A Pawtucket, had gone 171 at-bats between homers. ... Vargas hadn't given up more than four runs in a start this season. ... Red Sox manager Bobby Valentine said 3B Kevin Youkilis, on the 15-day DL since April 29 with a strained lower back, took groundballs Monday and isn't far away from returning. ... Wedge feels his struggling lineup needs a lot more help from Suzuki. "I'm hoping we can get a little more production out of the 3-spot, out of Ichiro, driving in runs," he said. "He's the one veteran we've got in the lineup and he has to produce for us." ... Wedge also said he sees improvement from 1B Smoak, who entered the game hitting .205. "He's been better. He's been more consistent to the point of contact." ... The Red Sox honored the 2012 NCAA Hockey champion Boston College Eagles before the game.