BOSTON – John Lackey is part of baseball’s only trio of starters with at least eight wins, and he thinks his best is still ahead of him.

Lackey pitched six innings, David Ortiz hit a two-run homer, and the Boston Red Sox beat the Arizona Diamondbacks 8-5 Thursday night to finish a three-game series sweep.

“It’s kind of exciting to be winning games right now because for my career I’ve always been better in the second half,” Lackey said.

Marco Scutaro had three RBI for the Red Sox (40-28), who moved a season-high 12 games over .500 with the ninth win in their last 11 home games but remained in third place in the American League East. Clay Buchholz (9-4) and Jon Lester (8-2) got the wins in the first two games of the series.

“If you run a good pitcher out there every night, it’s part of what we’re trying to do,” Manager Terry Francona said. “The wins and losses go further than that, though. You’ve got to have a bullpen that can hold leads.”

Lackey (8-3) labored through 112 pitches and earned the win when Adrian Beltre hit an RBI single in the sixth that gave the Red Sox a 5-4 lead. Scutaro added a sacrifice fly in the inning, driving Dan Haren (7-5) from the game.

Lackey allowed three earned runs and eight hits while becoming the 16th Boston starter in the last 18 games to work at least six innings.

“It was a battle for him to command his fastball,” Francona said. “He just has a way of managing the game and competing, and I think he’s going to get into a situation where he reels off a lot of zeros.”

Arizona extended its club-record road skid to 13 games, a streak that began after a May 17 win at Florida.

“It’s not so much about the road as much as finding ways to score runs when you have opportunities,” Arizona Manager A.J. Hinch said. “It’s frustrating. It doesn’t matter home or away, but the losses have piled up on the road for sure.”

Arizona fell to 9-25 away from Chase Field, the fewest road wins in the National League.

Ortiz reached base four times with a single, homer and two walks, one of them intentional. He is 11 for 23 with two homers and eight RBI in his last six games.

Ortiz’s numbers are up to .266 with 14 homers and 43 RBI. Through May 10, he was hitting .185 with four homers and 11 RBI.

“He looks like the old David,” Francona said. “He’s taken some ferocious swings.”

Ortiz connected in the third after Darnell McDonald reached on an error by third baseman Mark Reynolds. His drive to center on a full-count pitch gave Boston a 3-2 lead.

Arizona scored in the fourth and fifth to regain the lead. Kelly Johnson had a run-scoring single and Miguel Montero hit an RBI double to make it 4-3.

But Boston tied it at 4 in the bottom half on doubles by Daniel Nava and Scutaro, then went ahead with two runs in the sixth.

“We put together a lot of good at-bats,” Haren said. “We really made Lackey work hard. He settled in at the end and put up a zero in the sixth inning and I wasn’t able to do that. That’s where the game really turned.”

Haren allowed six runs, four earned, and seven hits in 52/3 innings.