BOSTON — 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.

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 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.

Lester didn’t allow a runner past second base until Justin Smoak doubled, moving Ichiro Suzuki to third with the one out in the ninth. Kyle Seager’s grounder scored the Mariners’ run.

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.

“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 Lester’s 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.