Sox pitcher Clay Buchholz chases a groundel hit by the Mariners’ Adrian Beltre. Buchholz made the play to first for the out.

AP / Elaine Thompson

SEATTLE — They rebounded from an 0-3 start to the second half of the season by winning three straight and salvaging the road trip. They get their most consistent run-producer back tomorrow after a nearly eight-week absence. Of their remaining 59 games, 34 are at Fenway Park, where they boast the best home record in baseball.

Maybe, just maybe, the Red Sox have turned the corner.

“I hope so,” said Mike Lowell after the third baseman’s bases-loaded, two-run single snapped a tie and sent the Sox on to a 6-3, 12-inning win over the Seattle Mariners yesterday. “We haven’t been able to get that 25- 30-game stretch where we can throw the same lineup out there, and we’re more than 100 games into the season.”

Yesterday, the Sox twice coughed up two-run leads and locked themselves into a battle of the bullpens with the Mariners.

Clay Buchholz, in his best outing since rejoining the rotation, carried them for 5 1/3 innings. Five Red Sox relievers then combined to provide 6 2/3 scoreless innings.

Until Craig Hansen staggered to the finish line in the 12th for his second career save, the Sox very nearly had 5 2/3 hitless innings. From the time Justin Masterson made his bullpen debut until Jonathan Papelbon got Kenji Johjima to bounce into a bases-loaded double play in the bottom of the 11th, the Mariners collected only three hits, and two of those never left the infield grass.

In the three-game sweep here — the Red Sox’ first sweep this season on the road — the Boston bullpen provided 10 scoreless innings, reinforcing manager Terry Francona’s belief that the answers to their relief woes are right in front of them.

“I always have (felt that),” said Francona. “I believe in them. On days when things don’t work, sometimes it’s a work in progress. But I’ve said all along that this could be a strength of this team.”

First, there was Buchholz, who enjoyed a blissfully uneventful first inning for a change and was done in by two poorly executed sinkers, which resulted in home runs — a solo shot by Raul Ibanez in the fourth and a two-run belt by Jose Vidro in the sixth, the later of which hastened his departure.

Inheriting a first-and-second, one-out mess, Masterson made his impact felt immediately. Showing the poise of a veteran, he promptly recorded two strikeouts, of Johjima and Bryan LaHair, on just seven pitches.

See how easy this relief thing can be at the major-league level?

“No, by no means is this easy,” said Masterson, chuckling at the thought. “But I was excited and the adrenaline took over. I just wanted to do the job and hold us in there.”

That he did, facing eight hitters over the course of three innings and retiring every one.

Francona said he didn’t start out intending to have Masterson pitch as long as he did, but once the rookie had some success “there was no reason to take him out.”

Hideki Okajima followed with two-thirds of an inning. Then came Manny Delcarmen — a perfect inning and a third with two strikeouts — and Papelbon, making his third appearances in as many days.

The Sox’ offense, meanwhile, had been shut down after reaching Felix Hernandez for two runs — just one earned — on an opposite-field single by Kevin Youkilis in the second that was atypically botched by Ichiro Suzuki. Another run came in the sixth on a bases-loaded walk to Coco Crisp.

Then, nothing. From the seventh through the 11th, the Sox mustered only two hits and had just one runner in scoring position.

But in the 12th, they began to stir. Jacoby Ellsbury singled, took second on a groundout and was joined on base by J.D. Drew, who was given an intentional walk.

Youkilis then drove a ball to deep center that Willie Bloomquist misplayed, filling the bases for Lowell.

“After (Seattle reliever Sean Green) missed with the first pitch 1-and-0,” said Lowell, “I felt like the pressure was on him to make a pitch.”

When he did, Lowell slammed it to left, scoring Ellsbury easily and Drew barely.

Sean Casey then provided some insurance when he greeted lefty Cesar Jimenez with a single to right, scoring Youkilis.

From there, they had only to weather Hansen’s rocky inning (two singles and a walk) before posting their third three-game road winning streak of the season.

Turning the corner? That remains to be seen. Heading for home? Certainly.

smcadam@projo.com