BOSTON — John Lackey felt a sense of relief following his first win in more than 20 months.
It wasn’t because of how well he pitched, either.
“I was relieved probably to know I’m going to get my next start, just to come out of it healthy more than anything,” Boston’s right-hander said with a laugh. “It’s been a long time. It’s nice to still be moving forward.”
Lackey allowed one run in six sharp innings in just his second start since 2011. Stephen Drew broke open a tie game in the fourth inning with a two-run triple and the sizzling Red Sox kept on rolling with a 6-1 victory over the Houston Astros on Sunday.
The 34-year-old Lackey missed the entire 2012 season after undergoing successful Tommy John surgery to reconstruct a torn ulnar collateral ligament in his right arm. He returned to the rotation Sunday for the first time since April 6 against Toronto when he left the game with a right biceps strain that landed him on the disabled list.
“A healthy John Lackey, and one who’s capable of a career that has been very good, he gives us a huge boost,” Red Sox manager John Farrell said. “I think we can all recognize the last couple years have been as much competing against his own body as it has been the opponent.
“He’s in a good place right now and there was no physical issues today.”
Four or five more starts, Lackey said, is what he needs to regain the arm strength he’s lost over the past couple of years.
It looked just fine Sunday.
Lackey (1-1) yielded five hits with two walks and four strikeouts to pick up his first win since Aug. 23, 2011, against the Texas Rangers, a span of 614 days.
“It’s been a lot of hard work to get back to this point,” he said, “and hopefully we can keep it rolling forward.”
Dustin Pedroia, Mike Carp and David Ortiz had RBI doubles for Boston, which won its fifth straight game and for the 15th time in its last 20 to improve to 18-7, the best mark in baseball. The 18 victories ties a club record for wins in April, established in 1998 and matched in 2003.
It also was the Red Sox’s third series sweep this season, tying the team’s total for all of last year.
“We’ve got one more game left in the month, but it’s been a very good one so far,” Farrell said. “I think this month has been a reflection of the work all of our guys have done in spring training, and it’s been buoyed by our rotation to be as consistent as it’s been.”
Perhaps even more impressive than its starting pitching, which improved to 15-4 this season, are Boston’s bats. The Red Sox exploded for 11 more hits Sunday and smacked 51 in the series.
The latest barrage has been led by Ortiz, who went 2-for-4 with an RBI single in the first inning to extend his hitting streak to 20 games dating to July 2, 2012, the longest of his 17-year career.
Despite missing 71 of the final 72 games last season and all of spring training with a heel injury, the 37-year-old Ortiz is hitting .516 (16 for 31) with five doubles, two home runs and 11 RBIs in eight games since returning to the lineup on April 20.
“We held it down until he got back and he’s doing his thing,” said first baseman Mike Napoli, who went 1-for-4 and leads the team with 27 RBIs. “He’s one of the greatest hitters in the game and it’s nice having him in there.”
The Astros, meanwhile, continue to struggle in their first season in the American League after the franchise’s first 51 years were in the National League. They’ve lost seven of their last nine games and 12 of 15 overall to fall to 7-18, the worst record in the AL and second worst in the majors.
“We’ve been battling and we wanted to put a W up there,” said Houston starter Bud Norris (3-3). “But we’ve got to put it behind us and get ready for the next day and try to end this skid.”
After allowing a run in the first inning, Lackey retired 14 of the next 15 batters he faced, including 13 straight, until Jason Castro singled with one out in the sixth. Carlos Pena and Ronny Cedeno followed with one-out singles to load the bases, but Lackey pitched out of peril, striking out Fernando Martinez and inducing Matt Dominguez to ground out on one pitch.
“It was definitely the first big challenge in a long time,” Lackey said. “To be able to get the strikeout and the ground ball to get out of there was a lot of fun.”
Norris’ first career start at Fenway Park wasn’t quite as memorable.
The right-hander surrendered five runs — three earned — and nine hits with two walks and six strikeouts in six innings.
Ortiz knotted the score with an RBI single in the first before Boston busted it open in the fourth, taking the lead for good when Carp and Jarrod Saltalamachia reached on consecutive singles and scored on Drew’s triple to the right-field corner.
Pedroia and Carp stretched the lead to 5-1 with run-scoring doubles to left field in the fifth, and Ortiz followed with an RBI double down the right-field line in the seventh.
“Guys aren’t afraid to pass the baton on to the next guy,” Farrell said. “They’ll take their walks in key spots and we’ve had good situational hitting.”
After getting two quick outs to begin the game, Lackey walked back-to-back batters before Cedeno delivered an RBI single up the middle for a 1-0 lead. Dominguez led off the second with a single, but that was it for Houston until the sixth.
NOTES: The Red Sox closed a 10-game homestand, their longest of the season, with a 7-3 record. … Boston has been in first place or tied for first all 28 days of the season, marking the longest continuous stretch that a Red Sox team has maintained first place to begin a season. The previous record was the first 25 days of the 1918 season. … The Astros fell to 0-7 all time at Fenway Park and 2-11 against the Red Sox overall. … Houston shortstop Marwin Gonzalez made two errors on one play in the bottom of the fifth. The first came on a grounder by Daniel Nava that Gonzalez failed to field cleanly, and he followed that with a wild throw to first that landed in the first row of seats directly behind Boston’s dugout. … Nava made a spectacular diving catch in right field to end the game.