Red Sox 6, Mariners 1 updated 9:04 p.m. BOSTON (AP) - Jon Lester pitched his second complete game of the season and Daniel Nava and Kelly Shoppach each homered, leading the Boston Red Sox to a 6-1 victory over the Seattle Mariners on Monday. 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. Ichiro Suzuki and Justin Smoak each had two hits for Seattle. Lester (2-3) 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 allowed eight hits and didn't walk a batter in his eighth career complete game. He struck out six. He threw 119 pitches. 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 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's 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. ... 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. ... Mariners manager Eric 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.