BOSTON (AP) -- Jon Lester felt he was in a perfect frame of mind. Now his teammates are feeling better about themselves at Fenway Park, too.
Lester held Seattle scoreless until the ninth inning en route to his second complete game of the season, helping the Boston Red Sox beat the Seattle Mariners 6-1 on Monday.
Lester (2-3) coasted through the first eighth innings, holding the Mariners to six singles and going to a three-ball count just twice.
"When you're working fast, it's a good thing to be able to pitch and not think about anything," he said. "Sometimes you have nights like this where things are going your way."
Lester allowed eight hits, struck out six and didn't walk a batter in recording his eighth career complete game. He retired the first nine batters easily, throwing 14 or fewer pitches in each of the first three inning. Lester threw 119 pitches over all.
"When you get the batters making early contact and fly balls guy after guy, it helps," he said.
Daniel Nava and Kelly Shoppach each homered for Boston, which has won four straight - all at Fenway.
David Ortiz and Adrian Gonzalez added consecutive RBI doubles for the Red Sox. Boston is on its longest home winning streak since capturing nine straight last July.
"We're trying to build a foundation of confidence in our team," Boston manager Bobby Valentine said. "When Jon is out there pitching like that, we feel very good about ourselves."
The Red Sox opened just 4-11 at Fenway.
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.
Ichiro Suzuki and Justin Smoak each had two hits for Seattle.
Lester didn't allow a runner past second base until Smoak doubled, moving Suzuki to third with the one out in the ninth. Kyle Seager 's grounder scored the Mariners' run.
He 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.
"I think every pitcher's goal is to go out and throw a no-hitter," he said. "You really don't think about it until the sixth inning."
"He did a great job of spotting his fastball both inside and outside to righties and lefties," Seattle manager Eric Wedge said, "and he cuts the ball every now and again. He did a good job throwing the breaking ball for a strike, but also throwing it on the plate, down, for some swing throughs. 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."
Seattle designated hitter Dustin Ackley was impressed by the lefties command, especially his cutter.
"That thing looked like his fastball and it just breaks off at the last minute," he said. "When you have a pitch like that, you're going to miss barrels a lot."
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.
Leading 2-0, the Red Sox increased their lead to 5-0 on the homers by Nava and Shoppach. Nava hit his into the first row of seats above the Green Monster after Cody Ross singled leading off for the second of his career. One out later, Shoppach belted one over the Monster seats, completely out of Fenway, for his first homer 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 Byrd 's sacrifice fly made it 6-0 in the eighth.
Boston had grabbed a 2-0 lead in the first on the doubles on consecutive pitches by 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. ... 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.