The Mariners look to hand the Red Sox an eighth straight loss for the first time in 11 years when the clubs continue their series Tuesday night.
After losing two of three over the weekend to the Los Angeles Angels, Seattle won for the 17th time in 20 home games with a 4-1 victory Monday.
Jason Vargas went seven innings to earn his 14th win as the Mariners (66-70) scored four times in the fourth.
It was the 14th time in the last 20 at Safeco Field that Seattle gave up two earned runs or fewer. The club has a 2.30 ERA during that stretch.
That number doesn't bode well for Boston (62-74), which had two errors in Monday's loss while dropping to 0-7 on a miserable road trip that ends Wednesday. The Red Sox have been outscored 58-16 during that stretch.
Coming off a series sweep in Oakland, which included a 20-2 defeat Friday, general manager Ben Cherington spoke of the team's struggles prior to Monday's game, admitting the Red Sox were "hard to watch."
Cherington was joined by principal owner John W. Henry on the third leg of the road trip, and addressed questions about manager Bobby Valentine's future.
"Bobby and I talked post-July 31 when things were not going as well as we're used to," Cherington said. "We talked about controlling things we can control and I told him we're both being evaluated on work we do every day."
Cherington, however, said a win-loss record is not a great way to judge a manager.
"It's always reflective to the talent on the roster. It's the work that gets done. We need the right work done every day,'' he said.
Looking to avoid its first eight-game losing streak since a nine-game skid Aug. 25-Sept. 4, 2001, Boston hands the ball to Jon Lester (8-11, 5.01 ERA).
Lester had a three-start winning streak snapped after he allowed five runs in eight innings of a 5-2 loss in Anaheim on Thursday. He gave up two runs in the first and two in the third.
"After the third, I was able to get in more of a rhythm and slow them down,'' said Lester, who had a 2.25 ERA over his previous three starts. "You've got to minimize the damage early, and I didn't do that."
The left-hander also had a complete game against Seattle on May 14, striking out six and scattering eight hits in the 6-1 win. He is 2-1 with a 2.01 ERA in the last four meetings against the Mariners, fanning 40 in 31 1-3 innings.
Blake Beavan (9-8, 4.95) counters for the Mariners, and he's looked much better since the All-Star break, going 5-2 with a 3.48 ERA in his last eight starts. He gave up two runs in seven innings of a 5-4 win at Minnesota on Thursday.
The right-hander, however, is 0-3 with a 6.35 ERA in three starts against the Red Sox. He allowed three runs and five hits in four innings of a 5-0 loss May 15 at Fenway Park.
Dustin Pedroia, who extended his hitting streak to 14 games Monday, is 3 for 9 against Beavan with two doubles.
- Seattle Mariners