SEATTLE -- Baltimore first baseman Chris Davis might not have the numbers that he did as a breakout star in 2013, but he continues to deliver in big moments.

The Orioles slugger led off the 10th inning with a home run, collecting his eighth game-winning RBI of the season in a 2-1 victory over the Seattle Mariners on Friday night.

"For me, this year has been a lot harder than I'd have liked it to have been," said Davis, who is hitting .203 after posting a career-high .286 batting average with a league-best 53 home runs last season. "Anytime I've had an opportunity to pick these guys up, I try to do it."

Davis drilled a 1-2 pitch from reliever Charlie Furbush over the left-field fence to break a 1-1 tie with his 17th home run of the season. Closer Zach Britton came on in the bottom of the inning to pick up his 19th save of the season after a replay overturn of a safe call at first base officially ended the game.

With two outs in the bottom of the 10th inning, Mariners second baseman Robinson Cano hit a soft grounder back to Britton, whose throw was a bit off the mark and drew Davis off the bag at first base. Cano was initially ruled safe, but a replay showed that Davis actually still had his foot on the base when the ball hit his mitt.

After a one-minute, 59-second replay review, the call was overturned, and the game officially ended.

"We had nothing to lose," Orioles manager Buck Showalter said of encouraging the umpires to look at the replay.

Baltimore (57-45) scored both of its runs on home runs, with designated hitter Nelson Cruz leading off the second inning with a 377-foot liner over the left-field fence for a 1-0 lead.

The Mariners (53-50) lost their fourth consecutive game while playing extra innings at home for the first time this season. Baltimore improved to 10-3 in extra-inning games, having now won five in a row.

Davis leads the team with eight game-winning RBIs.

"He's had some really big hits for us this year," Showalter said, "and tonight was another example."

Orioles reliever Darren O'Day (3-1) picked up the win after getting the final two outs of the ninth inning. Furbush (1-5) took the loss.

The Mariners' latest addition, designated hitter Kendrys Morales, drove in Seattle's first run in a span of 16 innings with a sacrifice fly in the sixth. Morales, acquired from Minnesota on Thursday for reliever Stephen Pryor, tied the score 1-1 after Cano led off the inning with a triple.

Morales looked like he might have a chance to be the hero in the bottom of the 10th inning when he stepped into the batter's box with two outs and Cano on first base after apparently reaching on an error. But Showalter came out of the dugout to argue the call at first, and umpires decided to look at a replay.

Davis said afterward that he wasn't certain whether his foot was on the bag when the ball hit his mitt. His momentum carried him forward as he reached out for Britton's throw, taking his foot off the bag.

Mariners manager Lloyd McClendon said of the overturned call: "I guess (Cano) was out. I didn't see the replay."

Seattle third baseman Kyle Seager went 2-for-4 with two doubles, but left fielder Dustin Ackley and first baseman Logan Morrison were a combined 0-for-3 with Seager in scoring position. The Mariners went 1-for-9 with runners in scoring position.

Mariners starter Felix Hernandez had another solid start, throwing seven innings of five-hit ball while giving up just one run.

It marked the 13th consecutive start for Hernandez in which he has allowed two runs or fewer and gone seven or more innings. Only Tom Seaver, in 1971, has pitched 13 consecutive games of seven or more innings and two or fewer runs since 1900.

Hernandez, who hasn't lost a start since June 13, struck out 10 batters along the way without issuing a walk.

"He pitched a great game," McClendon said. "He was outstanding."

Baltimore's Kevin Gausman had similar results in 6 2/3 innings, allowing just one run and seven hits. The score was tied 1-1 when Gausman and Hernandez gave way to their respective bullpens.

"I knew runs were probably going to be at a premium tonight, so I felt like I had to be at my best," Gausman said.

The Mariners, who had eight hits, have scored just four total runs during the four-game losing streak.

"It's just a tough stretch," McClendon said. "It'll pass. It's not pretty right now."

Seattle struggled to put runs on the board again Friday, going hitless in its first six at-bats with runners in scoring position. The Mariners finally delivered a clutch hit in the fifth, when center fielder James Jones hit a two-out single with right fielder Endy Chavez at second base, but Baltimore left fielder Steve Pearce gunned down Chavez at the plate to the end the inning.

One at-bat earlier, Chavez appeared to drive shortstop Brad Miller from first to third on a single, but Miller was called out because the line drive grazed his foot as he attempted to jump out of the way.

Cruz hit a solo home run on the first pitch he saw from Hernandez for his 29th homer of the season to lead off the second inning, giving the Orioles a 1-0 lead. The line drive barely cleared the wall in left, about 358 feet away.

Baltimore jumped on Hernandez early again in the third inning, when catcher Caleb Joseph led off with a double, but the Orioles eventually stranded Joseph at third.

NOTES: New Mariners DH Kendrys Morales reported to the team Friday afternoon and batted fourth in the lineup against Baltimore. Morales, who played with Seattle last season, was acquired from Minnesota for RHP Stephen Pryor on Thursday. ... Baltimore 3B Manny Machado (back spasms) was not in the starting lineup for the fourth game in a row Friday. ... Orioles DH Delmon Young was back on the bench Friday, one day after hitting a three-run homer in a 4-0 win over Seattle. ... Seattle sent DH Jesus Montero to Triple-A Tacoma on Friday, clearing a spot on the 25-man roster for Morales.