BALTIMORE — Boston's first game with its revamped bullpen coincided with its initial foray into an extra-inning game with baseball's new rules.

It did not go well.

Pedro Severino singled in the winning run in the 10th inning to punctuate a poor performance by Boston's relievers, and the Baltimore Orioles beat the Red Sox 5-4 Saturday night to snap a six-game losing streak.

Boston appeared poised to secure its fourth straight victory after starter Martin Pérez gave up five hits over seven innings and left with a 3-1 lead.

“Great outing," manager Ron Roenicke said. “It's just too bad he didn't get the win."

One night earlier, the rebuilding Red Sox traded veteran relievers Heath Hembree and Brandon Workman to Philadelphia for a pair of young starters.

So Josh Taylor entered with his 16.20 ERA to start the eighth inning. He got two quick outs before issuing a walk, and Anthony Santander followed with a game-tying homer inside the left-field foul pole.

Boston used three straight walks off Cole Sulser in the 10th to regain the lead, but in the bottom half Matt Barnes (1-2) let in the tying run on a wild pitch before Severino hit a liner to left-centre with the bases loaded, one out and five men in the infield.

“I’ve seen that before," Severino said. “The only thing in my mind was to get the ball on the barrel and just see where it goes. I didn’t try to do too much.”

The rules this year call for a runner to start on second base in extra innings, which proved “interesting" to Roenicke.

“I kind of liked it," he said. “You get after it right away."

Except that his new closer found himself in trouble before throwing his very first pitch.

“For Barnes, it's a tough situation to come into," Roenicke noted.

Miguel Castro (1-0) got the final two outs in the 10th to help the Orioles end their longest skid of the year. Manager Brandon Hyde went deep into his bench in an effort to secure the victory.

“Felt like our guys, we needed to celebrate tonight a little, we needed to feel a win," Hyde said. “So I was trying to give us every opportunity.”

Jackie Bradley Jr. homered and Alex Verdugo had two doubles and an RBI for the last-place Red Sox.

Pat Valaika put Baltimore up 1-0 in the second with his fifth home run, the most he’s had in a season since hitting 13 with Colorado in 2017.

Boston went ahead 2-1 in the fifth. Bradley sent a 2-1 pitch over the wall in centre — his first homer of the year — before José Peraza and Verdugo hit successive doubles.

Kevin Pillar drove in a run in the sixth with an infield hit.

Orioles starter Alex Cobb gave up two runs and six hits over five innings in another frustrating outing at Camden Yards. Since joining the Orioles in March 2018, the right-hander is 0-9 in 16 starts at home.

FIRST HIT

Orioles prospect Ryan Mountcastle got his first big league hit on a dribbler down the third base line in the ninth inning. In addition, teammate Ramón Urías celebrated his initial major league start with a third-inning single for his first hit.

ROSTER MOVES

Red Sox: Recalled LH Jeffrey Springs and RH Robert Stock to fill out the bullpen after Hembree and Workman were traded Friday night. The two pitchers obtained in the trade, Nick Pivetta and Connor Seabold, were optioned to the team’s alternate site.

Orioles: OF Dwight Smith Jr. was designated for assignment and the team selected the contract of OF Mason Williams from its alternate site. Williams “offers more versatility in the outfield," according to manager Brandon Hyde, which is important with CF Austin Hays (rib fracture) on the IL. “Selfishly, we hope he will remain in the organization after this designation period," GM Mike Elias said of Smith. “Great kid, great player.”

TRAINER'S ROOM

Red Sox: Manager Ron Roenicke said OF Andrew Benintendi (rib cage strain) “is certainly doing better" but was unsure if X-rays had been taken recently. Benintendi has been on the IL since Aug. 12.

Orioles: Chris Davis (knee) will be assessed on a week-to-week basis, Elias said, insisting there is no inclination at this time to shut down the slumping first baseman (.122, 1 RBI) for the season. ... Reliever Hunter Harvey (right forearm strain) is throwing to batters at the alternate site. “If everything progresses well, I think you'll see him by the end of the month," Hyde said.

UP NEXT

Red Sox: Zack Godley (0-2, 6.87 ERA) makes his fifth start of the season Sunday in the series finale.

Orioles: Wade LeBlanc (1-0, 7.89) beat Boston on July 26 and is 3-0 in six career starts against the Red Sox.

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