J.D. Drew and Victor Martinez each knocked in a run for the Red Sox, who have won three in a row and five of seven overall.
Lackey (12-7) gave up three runs -- two earned -- on six hits to win his second straight start. The right-hander also fanned a season-high 10 batters and walked two.
Casey Kotchman had two RBI for the Mariners, who have dropped three straight since a three-game win streak.Chone Figgins had three hits and scored a run.
Doug Fister (4-9) went 6 1/3 frames in the start, allowing five runs -- two earned -- on six hits. He also struck out six and walked one.
With the score deadlocked at three, the Red Sox scored three times in the seventh to take the lead. Jed Lowrieand Daniel Nava got things started with consecutive singles. A sacrifice bunt moved the runners up one base.Sean White relieved Fister and gave up a two-run single to Scutaro. Drew followed with a base hit to put men on the corners. Martinez then hit a sac fly. Adrian Beltre lined out to end the frame, but not before Boston took a 6-3 margin.
Jonathan Papelbon worked around a leadoff single in the ninth to record his 31st save of the season.
Seattle got on the board in the third. Ryan Langerhans walked and moved to second three batters later when Ichiro Suzuki was intentionally walked. Figgins followed with an infield single. Second baseman Lowrie's fielding error on the play allowed Langerhans to score.
Fister retired eight straight batters before Beltre led off a three-run fifth with a single. Two batters later, Lowrie reached base on left fielder Langerhans' fielding error. Nava walked to load the bases. After Ryan Kalish popped out, Scutaro hit a two-run single to right. Drew's RBI single gave Boston a 3-1 lead.
The Mariners plated two runs in the sixth to tie the game. Suzuki and Figgins started the inning with consecutive singles. Franklin Gutierrez reached first on Lackey's fielding error two batters later to load the bases. Kotchman followed with a two-run single to right. Adam Moore grounded into a fielder's choice and Langerhans flied out, but not before Seattle made it a 3-3 contest.
The Red Sox lead the season series with the Mariners, 3-2...Seattle was without outfielder Michael Saunders (right shoulder)...Boston has claimed outfielder Johnny Damon off waivers from the Detroit Tigers, and the veteran has until Wednesday to decide if he will waive his no-trade clause to re-join the club he helped win the 2004 World Series title...Lackey improved to 13-9 lifetime against the Mariners.
After dropping the opener of their set with the Toronto Blue Jays on Friday, the Red Sox managed to bounce back and win the final two games and got a terrific effort from Clay Buchholz in Sunday's rubber match. The right-hander tossed six scoreless frames and Bill Hall added a two-run home run in Boston's 5-0 win.
Buchholz (15-5) gave up five hits while fanning seven and walking three for the win, his fourth straight victory. He has now not allowed an earned run in 23 1/3 consecutive innings.
Hoping to keep the Red Sox in the win column tonight will be right-hander John Lackey, who is 11-7 with a 4.62 earned run average on the year. Lackey picked up a win on Wednesday against the Los Angeles Angels of Anaheim, holding his former team to five runs and 10 hits in seven innings of a 7-5 verdict.
Lackey is certainly no stranger to the Mariners, having pitched the first eight years of his career with the Angels in the AL West, and is 12-9 lifetime against them with a 3.70 ERA in 26 starts.
Seattle, meanwhile, will counter with righty Doug Fister, who is 4-8 with a 3.92 ERA. Fister did not get a decision last Monday in Baltimore, allowing three runs and 10 hits in five innings of his team's 5-4 setback.
Fister also did not receive a decision against the Red Sox earlier in the year, the only previous time he has faced Boston.
Seattle dropped two of three in New York over the weekend and fell 10-0 in Sunday's rubber match at Yankee Stadium. Luke French (2-4) was charged with the loss in that one as the Mariners fell to 5-4 on their current 12-game road trip.
The Mariners, who have won five of their last six series openers, have split their four meetings with the Red Sox this season.