KANSAS CITY -- The A’s placed outfielder Stephen Piscotty on the 10-day injured list retroactive to Sunday with a sprained right ankle, opening the door for a young outfielder who is putting up monster numbers at Triple-A Las Vegas.

Oakland promoted Seth Brown, a left-handed-hitting outfielder/first baseman who is tearing up the Pacific Coast League with 37 home runs and 104 RBIs to go with a .297 average over 112 games for Triple-A Las Vegas. He leads the PCL in RBIs and total bases (286), and he ranks second in home runs, extra-base hits (72) and runs (101), fourth in slugging (.634) and ninth in OPS (.986). Brown, who batted sixth and started in left field in his Major League debut in the A's 19-4 win over the Royals on Monday at Kauffman Stadium, logged a single off Brad Keller in his first at-bat and later scored in a five-run second inning.

Brown, who finished 2-for-6 with two runs scored, collected his first career RBI with a single in the third off Royals reliever Jorge Lopez.

To clear a spot on the 40-man roster, the A’s designated outfielder Nick Martini for assignment.

Piscotty returns to the injured list for the second time as he was out from June 30 to Aug. 2 with a sprained right knee. He hit .304 with four home runs and 10 RBIs in 16 games after returning from the IL and is batting .252 with 13 home runs and 44 RBIs in 92 games overall with the A’s.

Originally selected by Oakland in the 19th round of the 2015 MLB Draft, Brown wasn’t necessarily on the club’s radar prior to this season. He sits outside of their Top 30 prospects per MLB Pipeline and he did not receive an invite to Spring Training. Now, Brown is thrust into the middle of a playoff race as the A’s entered Monday just a half-game behind the Rays for the second American League Wild Card.

“It’s been an incredible journey for me,” Brown said. “I’ve got so many people to thank for support and help along the way. It’s been an incredible ride. To get this invite up here and try to help us win, it’s something you only dream about. It’s been a pretty emotional few days for me. But I’m up here.”

In his first Triple-A season, the 27-year-old has seen a dramatic increase in power. He hit 30 home runs with Class A Advanced Stockton in 2017, but that was the outlier from the rest of his seasons, which never saw him hit more than 14.

So what’s the reason for the big turnaround? Brown credited Triple-A hitting coach Eric Martins and Double-A Midland hitting coach Tommy Everidge for helping him make adjustments at the plate.

“For me, it was nailing down an approach,” Brown said. “Regardless of who’s on the mound, having the same routine day in and day out has been the biggest thing. Just nailing that down.”

Brown’s brother, Micah, who is an infielder in the Marlins' Minor League system, and their parents, John and Julie, were in attendance at Kauffman Stadium for Seth's Major League debut. Given that the A’s will face two more right-handed starters on Wednesday and Thursday, Brown figures to get plenty of opportunities to translate his big numbers to the Majors.

“Brown is up here to play, especially against right-handed pitching,” manager Bob Melvin said. “He’s a hard-nosed player and putting up great numbers. There are certain guys you feel really good about making their Major League debuts. We’re all excited about him being here.”

It wasn’t an easy decision for the A’s to part ways with Martini, who led off for them in the 2018 Wild Card Game at Yankee Stadium. It was the culmination of a breakout first season in the Majors that saw him hit .296 in 55 games. Martini had two stints with the A’s this season and he went 1-for-11 (.091) with a home run and two RBIs in six games.

“Nick was not only a good player for us, but fit in so well in this clubhouse. He understood how we did things and was ready for pinch-hit at-bats,” Melvin said. “This is a guy that led off in a playoff game for us last year. I’m certain it was a difficult one for the front office to come to the conclusion to take him off the roster. He’s been terrific for us.”