BOSTON -- Rick Porcello made the big pitches the Boston Red Sox needed Wednesday night.

Before the game, the scuffling right-hander's manager knew Porcello would have to deliver three or four big throws if Boston wanted to keep the good times rolling, and deliver he did.

Porcello escaped a bases-loaded jam in the fourth, forcing an inning-ending groundout to hold the Miami Marlins to two runs in the frame, and he snapped a career-worst seven-game losing streak as the Red Sox earned a 6-3 win to sweep a two-game series at Fenway Park.

"Those are the situations that any starting pitcher is going to face in the course of a game," Boston manager John Farrell said. "There's probably three or four of those opportunities that come up. Not only did he make the pitch, but he makes a heck of a defensive play to keep a potential two-run single (from) going through the middle."

Porcello (5-9) was 0-7 with an 8.18 ERA in his previous eight starts, but he turned in his best outing in more than a month Wednesday. He lasted six innings, allowing two runs on eight hits and a walk while striking out four.

"Just limited that big inning, that was it," Porcello said. "Other than that, just working on and executing pitches. (Catcher Ryan Hanigan) called a great game back there, just hung in there with him and focus on making pitch after pitch."

Boston (41-45) extended its winning streak to a season-high four games.

"We're on a pretty good stretch," Farrell said.

First baseman David Ortiz had two hits, including a two-run homer in the Red Sox's four-run third inning and a ground-rule double to the center field triangle in the sixth. Boston shortstop Xander Bogaerts and second baseman Brock Holt each drove in a run.

Koji Uehara picked up his 21st save by throwing a scoreless ninth inning.

Three errors proved costly for Miami (35-50), which got a commendable start from Tom Koehler (7-5) despite the loss. The right-hander surrendered five runs, only one of which was earned, on five hits and two walks while striking out two in six innings.

"(The Red Sox) are a good team with a good lineup," Koehler said. "Any time you give them extra outs, you really have to bear down and try to put up a zero, and I wasn't able to do that. They were taking advantage of mistakes."

Designated hitter Michael Morse hit a solo home run in the eighth to cut the Marlins' deficit to three. Miami left fielder Christian Yelich went 0-for-3, ending his nine-game hitting streak. Right fielder Ichiro Suzuki snapped a 29-at-bat hitless streak with a fourth-inning single.

"Just sloppy. It's really uncharacteristic of who we've been," Marlins manager Dan Jennings said. "We have to do a better job taking care of the ball. There's no excuse for that. Five of those runs were unearned. We are a better team than that."

The Red Sox jumped on top in the third. The rally was highlighted by a rare showing of opposite-field power from the aging Ortiz, normally the team's designated hitter. Ortiz stroked a 1-1 pitch into the Green Monster seats in left for a two-run homer, his 15th of the season.

Holt's groundout drove in the first run of the inning after a Koehler throwing error put runners in scoring position. Bogaerts later beat out an infield single to plate a run.

Miami got to Porcello in the fourth after he had breezed through the first three innings. Back-to-back singles set the table for catcher J.T. Realmuto, who singled to drive in the Marlins' first run. Center fielder Cole Gillespie's RBI single in the next at-bat made it 4-2.

NOTES: Boston became the last team in the majors to record a four-game winning streak this season. ... Miami lost its seventh in a row against the Red Sox and dropped its ninth consecutive interleague road game. ... Marlins 1B Jeff Baker did not play after leaving the game Tuesday with an oblique injury. Justin Bour started at first base and went 1-for-4. ... Red Sox manager John Farrell would like to get struggling 1B Mike Napoli back in the lineup before the All-Star break, but he started David Ortiz at first again. "We're not turning from Mike," Farrell said. ... Boston will take a day-by-day approach when 2B Dustin Pedroia (hamstring) is eligible to be reinstated from the disabled list Friday. ... The Red Sox acquired RHP Ramses Rosario from the Washington Nationals for an international bonus pool slot in the 2015-16 signing period.