WASHINGTON: Washington outfielder Bryce Harper and teammate Jonathan Papelbon got into a fight during a game Sunday, when a Nationals season that long ago spiraled out of control on the field did so in the dugout.

After a flyout in the eighth inning of what became a 12-5 loss to the last-place Philadelphia Phillies, Harper headed to the dugout, where he and Papelbon, the team’s closer, exchanged words. The argument escalated, and Papelbon reached out with his left hand and grabbed Harper by the throat.

Papelbon then shoved the outfielder toward the bench with both hands, before teammates pulled the pair apart.

“I’m in the wrong there,” Papelbon said afterward. “For me, I can’t allow that to happen in the middle of a game. You can handle that after the games or allow the manager to handle that.”

In the ninth, Papelbon (4-3) gave up Andres Blanco’s go-ahead homer as the Phillies scored eight times.

Harper, the National League Most Valuable Player front-runner, was replaced in right field for the ninth.

Elsewhere, Chicago stopped Pittsburgh’s winning streak at eight games with a 4-0 win, Houston maintained a half-game lead over the Los Angeles Angels for the second American League wild card with a 4-2 win over Texas, and the Angels kept pace with a 3-2 victory over Seattle.

In Chicago, Jake Arrieta pitched seven dominant innings and also homered in his MLB-best 21st win for the Cubs.

Arrieta (21-6) retired his first 18 batters before Gregory Polanco grounded a leadoff single into left field in the seventh. The right-hander homered in the second and struck out nine while improving to 15-1 with a dazzling 0.89 ERA in his last 19 starts.

Pittsburgh (95-61) and Chicago (90-65) each have clinched playoff spots and lead the NL wild-card standings, so the Pirates could see Arrieta again in the first game of the postseason on Oct. 7.

The Pirates could still catch St. Louis for the NL Central title. After the Cardinals’ 8-4 loss to Milwaukee, Pittsburgh trailed by just three games. The teams open a three-game series on Monday.

In Houston, Dallas Keuchel (19-8) improved to 15-0 at home this season, striking out 10 while giving up one run and two hits in seven innings.

The Astros closed within 2 1/2 games of AL West-leading Texas with the win.

Los Angeles won its fifth straight to stay in the AL wild card race, too.

Kole Calhoun singled in the tiebreaking run in the eighth and David Freese homered in the fifth for the Angels (81-74), who also moved just three games behind the Rangers, with four games in Texas to end the season.

Minnesota also remained in contention for the postseason with a 7-1 win over Detroit. Byron Buxton doubled and homered for Minnesota, which won for the fifth time in seven games and remained 1 1/2 games behind Houston.

Elsewhere, Kansas City’s Chris Young (11-6) pitched five no-hit innings a day after his father died, then caught a flight to Dallas to be with his family before the end of the Royals’ 3-0 victory over Cleveland. It was Young’s first start after nearly two months in the bullpen.

New York’s Luis Severino (5-3) pitched five-hit ball for six innings and Dustin Ackley homered as the Yankees closed in on at least an NL wild card with a 6-1 win over the Chicago White Sox. The Yankees also moved within one of the club’s 10,000th regular-season victory.

Josh Donaldson hit a solo homer off Steve Geltz (2-6) with two outs in the ninth — his 41st this year — as playoffs-bound Toronto defeated Tampa Bay 5-4. The Blue Jays, headed to the postseason for the first time since 1993, finished an AL-best 53-28 at home.

A day after clinching the NL East title for their first postseason berth since 2006, the Mets rested their regulars but still completed the season sweep over Cincinnati with an 8-1 win. It was the first sweep by either team since New York started play in 1962, going 7-0 against Cincinnati.

In other scores, Boston beat Baltimore 2-0, Miami defeated Atlanta 9-5, Colorado topped the Los Angeles Dodgers 12-5, San Francisco beat Oakland 5-4, and Arizona outlasted San Diego 4-2.