OAKLAND -- Zack Greinke's last relief appearance was in 2021, when he pitched out of the Houston bullpen twice: once on Oct. 3 and a week later, on Oct. 10, in Game 3 of the AL Division Series against the White Sox. 

Prior to that, it had been over a decade since Greinke last pitched as a reliever, when he made 38 relief appearances during his fourth big league season for the Royals in 2007.

So it really was vintage Greinke who showed up Tuesday night.

Back from the 15-day injured list to pitch against the A’s, Greinke entered in the fourth inning and turned in four scoreless frames with five strikeouts in the Royals’ 5-4 loss at the Oakland Coliseum. The A’s scored five early runs against starter Angel Zerpa (four earned) in three innings, but were held to just two hits after that.

“It’s the same,” Greinke said about relieving versus starting. “Only difference, I guess, is that you’ve got a less exact time the game is going to start for you. So it’s a little bit trickier timing it to get ready.”

Greinke and the Royals have explored using an opener earlier this season before he hit the IL on Aug. 7 with elbow soreness, and the veteran starter has been willing to discuss it.

Given his physical limitations, now in his 20th season and at 39 years old, using an opener could benefit Greinke, who wouldn’t have to go through the lineup three times and could perhaps receive more favorable matchups later in the game.

“He’s actually explored it with us earlier in the year just because of how he feels about himself and where his stuff is,” manager Matt Quatraro said. “And how much homework he does on how to pitch to certain players, talking about different lineups and matching up.”

Greinke added postgame: “I don’t really think too much about it. When you’re a superstar pitcher, you can pitch more pitches, face more batters and throw more innings. And when you’re not as good, they kind of have to figure out ways to help the team win. Sometimes it might be better to do that. Sometimes it might be better to start. I don’t know. But that’s kind of the goal.”

Zerpa was utilized as more of an extended opener with his three innings, but the A’s hit him hard. His outing began with a hit batter and a walk, both of which came around to score on Brent Rooker’s RBI single and Aledmys Díaz's sacrifice fly.

The Royals tied it in the top of the second, but Zerpa gave it right back on Shea Langeliers’ 113.4 mph home run, before the A’s added on in the third when third baseman Maikel Garcia made an error, followed by back-to-back hits.

“You have to attack the strike zone and execute your pitches,” Zerpa said.

Greinke ended the A’s scoring with swing-and-miss stuff, registering a 33% whiff rate. He was efficient until the last batter he faced, Carlos Pérez, who struck out swinging through a 72.4 mph curveball as the eighth pitch of the at-bat.

Greinke spiked a couple of breaking balls earlier in the at-bat, which frustrated him and might have signaled his fatigue after not pitching in a game for over two weeks. Greinke ended his outing at 53 pitches, right around his pitch limit.

“The ball just started slipping out,” Greinke said. “Maybe I was tired. I don’t know what happened. It was a longer at-bat, and I pulled one three feet sideways and then threw one straight in the air, so I don’t know. It was frustrating, though.”

Frustration was evident after Tuesday's defeat. The Royals have now lost 10 consecutive games decided by two runs or fewer, which is a franchise record.

And they’re 2-8 in those games -- including two straight to the A’s, who have the only record worse than the Royals’ 40-88 mark this season.

“These games, they’re all different,” Quatraro said. “... We just didn’t have enough to get it over the top tonight. There’s no one answer. It’s just playing clean baseball.”

Kansas City went 3-for-9 with runners in scoring position and left seven on base Tuesday.

“They made pitches tonight,” said second baseman Michael Massey, who executed another web gem in a play with Bobby Witt Jr. to retire Ryan Noda. “Did a good job working both sides of the plate, changing speeds, and we didn’t do a great job of adjusting to it. …

“We’ve got to be better. In those moments, we’ve got to step up and start making plays.”