BOSTON -- If there was any concern about Justin Masterson breaking down as the season progresses and as the 26-year-old approaches a career high in innings, he's done everything to silence it over the past two months.
Masterson threw his fourth straight quality start on Thursday night, lowering his ERA over his past dozen outings to 1.97 with six innings of three-run ball against the Red Sox. It was enough to pick up his ninth win of the season, while Travis Hafner and Carlos Santana spoiled Erik Bedard's Red Sox debut in the 7-3 victory.
"I started off the season 5-0, but as the season's gone on, I felt like each time, every month, I feel better and better, under control, making good pitches and things like that," Masterson said. "I feel like, as the season's gone on, I've gotten better in the whole aspect of pitching."
Approaching 160 innings with two months of the regular season still to play -- and potential postseason participation looming -- Masterson said that his body will be ready to shoulder whatever the team needs of him.
"I think so," he said. "God blessed me with a 6-6 frame, 250 pounds. So hopefully, with the hard work and things I've been doing, it'll keep me strong till then."
And with Ubaldo Jimenez set to make his Indians debut on Friday, Masterson reminded his manager that the Indians now have a pair of aces hoping to propel them to their first postseason since 2007.
"Right now our main guy has been Justin Masterson," said skipper Manny Acta. "He's a guy that ... for a while now, we've tried to keep him on the five-days routine, because he's the guy.
"Ubaldo doesn't have to feel like he's the guy that has to stop it every time. Having him and Justin back to back every week gives us an opportunity to avoid any type of slumps."
Masterson shook off a rough first inning, in which Adrian Gonzalez and David Ortiz plated a pair of runs, and was electric from there on out. It took him four strikeouts to get through the second, though, as catcher Santana couldn't handle a slider that whiffed Josh Reddick, allowing him to reach base on the wild pitch.
Masterson allowed just two hits the rest of the way.
Reddick connected on a low fastball in the fourth for his fifth homer of the year, but that was all the Sox would muster off their former teammate. The homer was the first allowed by Masterson since July 1, a span of 44 2/3 innings. He's allowed just five all season.
Scoring seven runs was especially encouraging for the Indians, who struggled to get any type of offense together during their most recent homestand, in which they scored three runs or fewer in seven of eight games.
The Indians struck early off Bedard, taking advantage of a defensive blunder to score a pair in the second inning. Santana squeaked a ground ball through the left side of the infield, and Kosuke Fukudome knocked a single to right field to move him to third. Matt LaPorta then smacked a slow roller to the first-base side, but Gonzalez moved off the bag, reaching in front of Dustin Pedroia to get the ball while no one covered first base.
The Indians grabbed the lead in the third off three base hits by Jason Kipnis, Hafner and Santana.
Red Sox relievers had kept the Tribe silent the past two nights, but the Tribe finally got to them on Thursday.
With Bedard removed after five innings, lefty Franklin Morales took over and promptly allowed a double to Hafner and a long home run to Santana. The drive to deep-center was Santana's 16th of the season and first since July 17.
"That's what baseball is all about," Acta said of his struggling but full-of-potential catcher, who is hitting just .232. "He came in early today and took some extra BP and bounced back. It's always good to see the young kids after they have a rough night like he had last night [0-for-4 with four strikeouts] come back the next day and be able to contribute so their confidence doesn't disappear."
The Indians plated a sixth run off Andrew Miller in the seventh, off the bat of Hafner, who finished the game 3-for-4, with every hit coming off a left-hander.
"He's been better this year, it's not a secret; he's healthier," Acta said. "If you remember, last year we got to a point, due to his health and struggle against lefties, where we almost had to platoon him for a while."
"I feel pretty good off them lately," said Hafner, who raised his season average against lefties to .257. "I don't think I've had a lot of success, but I feel like I've had a bunch of good at-bats, and I've hit some balls well. And I haven't really had any hits, so it was good tonight to swing the bats well off them."
Masterson needed a season-high 118 pitches to get through the night before turning it over to the bullpen, which put up its first zero of the series.
Masterson's outing pushed him to 3-0 in four career starts against his former team, with 21 strikeouts and a 1.95 ERA in 27 2/3 innings.
"He's good, and we see his best," said Red Sox manager Terry Francona. "I'm sure he enjoys pitching against us. He's really good. The things he needed to work on when he was a young pitcher -- getting in to lefties -- he can do that now. He's not timid throwing it in, and he can elevate when he wants to. He's impressive."
The Indians improved to 40-3 this season when leading after six innings, and the win gave them a crucial split in the four-game series before they head to Texas to play the first-place Rangers.
"I never felt better after splitting the series than this time," Acta said. "We pitched our [tails] off, and these guys played their hearts out against a very good ballclub."
"It's definitely a confidence booster," Hafner said. "We really needed to get our bats going. I'm just happy to see the offense get going a little bit. The pitching staff did great, so hopefully we can just continue this."
Jason Mastrodonato is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.