LOS ANGELES — Max Muncy’s three-run double highlighted a five-run fifth inning, Shohei Ohtani stole his 39th base of the season, and the Los Angeles Dodgers beat the Seattle Mariners 8-4 on Wednesday night to complete a three-game sweep.

Ohtani is just one stolen base and one home run away from becoming the fastest player in major league history to reach 40-40. The Japanese superstar would be the first player in Dodgers history to do so.

The NL West leaders outscored the Mariners 17-7 in the interleague series. The Dodgers won their fourth in a row to increase their lead over Arizona and San Diego to four games.

“What we did with those starters this series was a clinic,” Dodgers manager Dave Roberts said. “You could argue that starting staff over there is top-two baseball. Grinding those guys, getting to the pen was one of our more impressive three-game series as far as beating the starter.”

Related Story: Pinch-Hitter Jason Heyward Delivers 3-Run Homer in 8th as Dodgers Rally to Beat ...

Up Next

Dodgers: After an off day, RHP Bobby Miller (1-3, 8.02) starts Friday against Tampa Bay.

Mariners: They’re off Thursday before RHP Luis Castillo (10-12, 3.51 ERA) starts Friday against San Francisco.

Flaherty Shines, Mariners Struggle

Dodgers starter Jack Flaherty (10-5) allowed two runs — one earned — and five hits in 5 2/3 innings. The right-hander struck out five and walked one.

The reeling Mariners have lost three in a row and eight of nine. They went 1-8 on their trip to Detroit, Pittsburgh and L.A.

The Dodgers stretched their lead to 8-1 with two outs in the fifth. Freddie Freeman’s RBI double scored Ohtani, who singled, stole second and took third on Logan Gilbert’s wild pitch.

Freeman scored on Hernández’s RBI single after taking third on another wild pitch by Gilbert. Muncy’s double into the right-field corner drove in three more runs.

“They have a really good pitching staff over there, arguably the best in baseball, and to be able to just get a couple good swings off felt really, really good,” said Muncy, who came off the injured list earlier this week after missing nearly three months.

Related Story: Gavin Stone Strikes out 10 as the Dodgers Beat the Mariners in Justin ...

Gilbert Struggles, Dodgers Capitalize

Gilbert (7-10) retired the first six Dodgers before they scored in each of the next three innings. The right-hander gave up eight runs and seven hits in 4 2/3 innings, struck out seven and walked two. He had three wild pitches, all of which led to runs.

Will Smith’s sacrifice fly to the warning track in center extended the Dodgers’ lead to 3-1 in the fourth. Teoscar Hernández walked, stole second and took third on Gilbert’s wild pitch.

The Dodgers took a 2-1 lead on a hard-hit double into the left field corner by Mookie Betts with two outs in the third. Kevin Kiermaier reached on a fielding error by shortstop Leo Rivas and Ohtani walked and scored from first without a play at the plate.

Related Story: Ohtani Hits 39th HR and Kershaw Pitches Dodgers to Win Over Slumping Cardinals

Tensions Rise Between Flaherty and Arozarena

The Mariners led 1-0 on Dominic Canzone’s sacrifice fly that scored Randy Arozarena, who was hit by Flaherty and then stared down the pitcher and stole second in the second. Arozarena appeared to take exception after being struck by the 2-2 pitch from his former teammate in St. Louis.

“I respect Randy as a player,” Flaherty said. “There’s no reason for me to hit him in that position and he took exception to it.”

Arozarena flied out to end the third and never made it to first while chirping at Flaherty. Both benches emptied but the umpires got in the middle and nothing happened.

Asked what he said to Arozarena, Flaherty said, “It doesn’t matter. It’ll stay between the lines.”

Fans booed Arozarena when he came up in the sixth. Flaherty walked him and the outfielder dumped his bat and strolled to first. After the Dodgers’ big fifth, Arozarena walked slowly in from left field as Hernández came out to take up his spot and they spoke to each other.

Trainer’s Room

Mariners: OF Victor Robles (hip flexor strain) sat out after getting hurt Tuesday while colliding with the wall in center trying to make a catch. He’ll be re-evaluated Thursday.

Dodgers: INF Miguel Rojas got the day off because of a left hamstring issue. He’s expected back in the lineup Friday. … Activated RHP Blake Treinen after he missed 14 games with right hip discomfort.