BALTIMORE — Alex Gordon had already compiled a career’s worth of playoff memories when he stepped to the plate in the 10th inning of a tie game.

Given the Kansas City Royals’ success rate in extra innings this postseason, what happened next was almost inevitable.

Gordon homered to put Kansas City in front, Mike Moustakas added a two-run shot and the Royals defeated the Baltimore Orioles 8-6 Friday night in the opener of the AL Championship Series.

Kansas City is 5-0 this postseason, winning four times in extra innings.

“These games, we’ve played so many of them that we’re kind of used to them a little bit,” manager Ned Yost said. “And we still have a lot of confidence.”

Before hitting his first playoff homer, Gordon doubled in three runs, was picked off first base, made a great catch in left field and got hit in the neck with a pitch.

“Gordy just has a lot of confidence in his abilities,” Yost said. “He’s a guy that can hit by a pitch and do exactly what he did, drive it out of the ballpark tonight, after getting hit in the neck. So it was a huge hit for us at that point.”

As the ball soared over the wall, Orioles reliever Darren O’Day flung his cap to the ground in frustration.

“I made a mistake and he got it,” the right-hander said. “You go up there and roll the dice. Sometimes you win, sometimes you lose.”

It was Baltimore’s first playoff loss following a three-game sweep of Detroit in the Division Series.

“One game does not the series make,” Orioles catcher Nick Hundley said.

After Gordon connected in the 10th, Moustakas followed with another shot to right, this one off Brian Matusz with a runner on.

This best-of-seven series was billed as Kansas City’s speed against Baltimore’s power, but the Royals didn’t steal a base and hit all of the game’s three home runs.

“We know we’re capable of hitting home runs,” Gordon said. “We didn’t do it during the regular season. But it doesn’t really matter. This is the postseason and we’re starting to swing the bats better now. It’s good to see.”

The Orioles tried to rally in the 10th. Pinch-hitter Delmon Young hit an RBI single with two outs, but closer Greg Holland retired Nick Markakis on a grounder with two runners on for the final out in the rain shortly before 1 a.m.

Game 2 is Saturday afternoon. Rookie right-hander Yordano Ventura makes his second postseason start for the Royals against Bud Norris.

Wade Davis got the win with two shutout innings and Holland got a save.

The fastest team in the majors nearly walked to victory in the ninth. After Orioles closer Zach Britton issued three straight walks to open the inning, Eric Hosmer into a force at the plate — helped by Hundley’s nifty pickup at the plate — and O’Day got Billy Butler to hit into a double play.

O’Day wasn’t nearly as effective in the 10th.

Down 5-1 in the fifth against James Shields, the Orioles scored three times as 47,124 towel-waving fans cheered them on. Nelson Cruz hit an RBI double before Ryan Flaherty delivered a two-out, two-run single.

Shields made it out of the inning, but did not return after giving up four runs and 10 hits.

The rain that was expected for much of the day finally made an appearance in the sixth, shortly before Baltimore pulled even against the usually reliable Kansas City bullpen. The tying run scored off Kelvin Herrera on a low popup by Alejandro De Aza that dropped behind the mound.

Early on, Kansas City dominated.

After the Orioles left the bases loaded in the second inning, Alcides Escobar drove a 2-0 pitch from Chris Tillman into the left-field seats. It was his 22nd homer in 2,994 career at-bats, including this postseason.

Kansas City then sandwiched two singles around a four-pitch walk to load the bases with two outs for Gordon, who lofted a broken-bat fly that landed about four feet inside the right-field foul line for a 4-0 lead.

Gordon also hit a three-run double in the finale of Kansas City’s three-game sweep of the Angels in the Division Series.

Baltimore got an RBI single from Adam Jones in the bottom half, but a diving catch by Gordon prevented further damage.

A sacrifice fly by Butler in the fifth made it 5-1.

UP NEXT

Royals: In two starts against the Orioles this season, Ventura has a 1.26 ERA and 17 strikeouts in 14 1-3 innings.

Orioles: Baltimore tries to rebound from its first loss since Sept. 27. The last time the Orioles lost the opener of an ALCS was when 12-year-old Jeffrey Maier got involved with a Derek Jeter home run at Yankee Stadium in 1996.

LIGHTS OUT

The start of the game was delayed while the bright lights above a TV booth in center field were shut down, one by one.

Escobar was about the step into the batter’s box when he noticed the glaring bulbs in his sight line. While Tillman took a few extra warmup tosses, the song “Lights” by Journey played over the PA system.