BALTIMORE -- After overcoming an early four-run deficit Wednesday against the Seattle Mariners, the Baltimore Orioles are developing a swagger that could serve them well during the final month of the season.

"We know we can do it," second baseman Jonathan Schoop said after his game-winning single in the bottom of the eighth inning lifted the Orioles to an 8-7 victory over the Mariners at Camden Yards and extended their winning streak to a season-high seven games.

Schoop was part of a home-run barrage the helped the Orioles (68-65) dig out of a 6-2 deficit against the Mariners and remain within two games of the second wild card in the American League playoff chase.

The Orioles clubbed four homers and now have hit 80 since the All-Star break in mid-July, which is the most in the major leagues by a wide margin.

Welington Castillo hit his 16th home run as part of his 4-for-4 day. Trey Mancini hit his 23rd homer and Craig Gentry his second to help assist the comeback effort.

"It's no surprise because we know we are a good team," said Schoop, who shares the team lead in homers (30) and has the most RBIs (99). "We have to just keep it up and keep winning series and keep winning series. We are going to be right there."

The Mariners (66-68) made the Orioles work for it, first with a six-run third inning that saw 10 batters come to the plate and then with a late home run by Mitch Haniger that tied the score at 7 in the top of the eighth.

But the Mariners fell for the fifth consecutive game. They capped a 14-day, 12-game road trip at 5-7. They traveled 7,500 miles during the course of the trip.

"We just weren't able to get through it today," Seattle manager Scott Servais said. "But we'll regroup. Off day tomorrow, come back home, long homestand and get it going there."

Haniger had three hits for his 17th multi-hit game of the season. He had a two-run double to left in the third inning, a leadoff double in the sixth and the game-tying home run in the eighth.

Ariel Miranda, making his first start against his former team, couldn't hold the lead for the Mariners. He gave up all four of the Orioles' home runs and lasted just 4 1/3 innings.

Seattle also got bad news when relief pitcher David Phelps reinjured his right elbow during just a third of an inning of work.

"This arm just doesn't want to get extended," said Phelps, who came off the disabled list Aug. 23. "It's frustrating. I'm out there trying to help the team win a ballgame and that happened."

The Orioles, meanwhile, overcame a poor start by Ubaldo Jimenez. He lasted just 2 2/3 innings after allowing six earned runs and six hits. It was his shortest start since June 23.

Jimenez was victimized by some bad luck. He watched a potential double-play ball off the bat of Nelson Cruz carom off the bag at second and out of the reach of his infielders, allowing two runs to score as part of the Mariners' six-run third.

"I thought it was a sure double play," Jimenez said. "We have a slow runner on first base, and Nelson is not the fastest guy either, but it went their way."

After pulling even with Schoop's fifth-inning blast, the Orioles went ahead 7-6 with one out in the bottom of the sixth on a sacrifice fly to right by Manny Machado.

Haniger gave Seattle life again with two outs in the bottom of the eighth when his ninth home run of the season landed just over the wall in center off Orioles reliever Brad Brach.

But the increasingly relentless Orioles answered right back.

Castillo, who matched a career high with four hits in the game, singled to right to open the bottom of the eighth. After advancing to second on a sacrifice bunt by Gentry, Castillo was replaced by pinch-runner Caleb Joseph.

Tim Beckham then lined a ball to Mariners shortstop Taylor Motter for the second out. Motter flipped the ball over to Robinson Cano at second to double off Joseph, and he was called out to apparently end the inning.

However, the call was challenged and eventually overtuned by replay. Joseph stayed at second and then came home as the winning run when Schoop pushed a single into left field off Mariners reliever Marc Rzepczynski.

"This is a very mature group," Orioles manager Buck Showalter said. "They have been through the battles in August and September. They realize what has to happen to roll the dice (in the playoffs) in October."

NOTES: The Mariners made a move to bolster their injury-plagued pitching staff by acquiring RHP Mike Leake from the St. Louis Cardinals for minor league infielder Rayder Ascanio, cash and $750,000 in international bonus slot money. Leake (7-12, 4.21 ERA) will likely make his first start for the Mariners this weekend against Oakland. ... C Welington Castillo and RF Craig Gentry connected for back-to-back home runs in the bottom of the fourth inning, marking the 11th time the Orioles have hit back-to-back home runs this season. ... 2B Jonathan Schoop drove in two runs to extend his Orioles record for most RBIs in a season by a second baseman. ... LHP pitcher Ariel Miranda made his 37th major league start but first against the Orioles, the team that traded him on July 31, 2016, for left-handed starter Wade Miley. The four home runs surrendered by Miranda were a career high for a game. ... The Orioles swept the Mariners for the first time at home since Aug. 6-8, 2012.