KANSAS CITY -- With so much attention on their upcoming three-game series with the Yankees, the A's four-game series finale with the Royals that preceded it had all the makings of a potential trap game. But manager Bob Melvin has often stated one of his club's strengths is the ability to take things one game at a time, and that's exactly what transpired.

On the eve of their first visit to Yankee Stadium since their loss in the 2018 American League Wild Card Game, the A's capped off a series victory with a 9-8 win over the Royals at Kauffman Stadium on Thursday. The win keeps Oakland in sole possession of the second AL Wild Card.

• Box score

"We had to win this game today," Melvin said. "We go through our entire plus-bullpen guys and have to cover five-plus innings. Now we're going into Yankee Stadium for three games against them, with the way they swing the bat. We had to win today."

"Anytime you can take three of four from a team this late in the season, it's huge," A's closer Liam Hendriks said. "We're not scoreboard checking or anything like that, but you take three of four, you'll do all right in the long run."

• Obscure rule nets A's valuable insurance run

It wasn't easy for the A's, but they managed to stave off the Royals after some more heroics from Hendriks.

Summoned in the eighth to get out of a jam that saw Jake Diekman surrender an RBI single to Nick Dini that shrunk Oakland's lead to two runs, Hendriks recorded his third five-out save of the year.

"Liam Hendriks showed up big for us," Melvin said. "The weather out there, that's a grind. You have to dig deep in that atmosphere, and everybody did."

Since taking over for Blake Treinen as closer on June 22, Hendriks leads the Majors with 17 saves.

"He's having a career year and we're just riding him," A's starter Chris Bassitt said. "It's not really surprising anymore. He's been dominant."

The A's received contributions up and down the order, with eight of nine batters in the starting lineup recording at least one of the club's 12 hits on the afternoon. Jurickson Profar provided one of the biggest, smashing a two-run blast off Royals starter Glenn Sparkman. The 1-1 changeup left over the heart of the zone was drilled 101 mph off the bat and splashed into the right-field fountains at a projected 411 feet, according to Statcast.

Profar's homer, his 17th of the year, was part of a three-hit day with three RBIs. He also brought home a run after getting hit by a pitch in the first, marking the 71st hit-by-pitch for A's batters this season, tied with the Twins for most in the AL.

"We've seen him have some big games on offense, but it just seems like he's into it right now," Melvin said of Profar. "It just feels like this is his best work during this stretch. He's showing up at the right time for us."

Leading the way in hits was rookie Seth Brown, who turned in a four-hit effort to become just the third A's player to record four hits in one game within his first four career games.

Brown also scored three runs, with his final run scored in the ninth the most important, and perhaps one of the more bizarre seen this season, as it provided Hendriks some extra breathing room.

Royals third baseman Cheslor Cuthbert chased down a pop up hit in foul territory by Corban Joseph before making the catch for the second out of the ninth. But according to Rule 5.06(b)(3)(C), which states if a fielder, after having made a legal catch, should step or fall into any out-of-play area, which Cuthbert did by jumping into the A's dugout, the ball is dead and each runner shall advance one base. Brown was on third base at the time, and the rule violation called by third-base umpire Chris Segal allowed him to score, giving the A's a two-run lead.

"I knew it right away, but you don't see it very often," Melvin said. "Chris was right on it. That's a huge play, obviously, to get that second run."

Brown said he was aware of the rule, as were the rest of his teammates in the dugout, most of whom immediately pointed to home plate after watching Cuthbert land on their side.

"That was my first one," Brown said when asked if he'd ever scored on a ball caught out of play. "It was really nice, actually."

Cuthbert, however, wasn't aware of the rule.

"At one point when I was getting close to the ball, I looked down to see where I was at -- if it was going to be a tough play," Cuthbert said. "That's why my first instinct was to hold onto the railing to not fall into the dugout. When the ball was coming down, that's the only shot I had.

"Then the umpire said the runners were going to advance a base. I didn't know about that rule. Every day you learn something in baseball."

Royals manager Ned Yost said even if Cuthbert knew the rule, there's not much a fielder can do.

"That's not a play [where the ball] goes up and you stop and think about your options, like, 'Um, do I let it fall? Do I catch it and go in?'" Yost said. "It's an instinctual play. You try to catch the ball. He caught the ball. He tried everything he could to hold himself back. But that's the way things go for us. … It couldn't have been a foot one way or the other. He just went right in the dugout."

With the series against the Royals in the rearview mirror, the A's now turn their attention to the Yankees, who were off Thursday. It's not the ideal situation for Oakland, which used four relievers to cover 5 1/3 innings in relief of Bassitt.

"They ate a ton of innings this series," Bassitt said. "Hopefully the starters can go a little bit deeper."