BOSTON -- Who knew the only thing Colton Cowser needed to tap into his power was a little friendly competition via the arrival of his good friend Jackson Holliday?

¡°As soon as Jackson got called up, I was messing around and I was like, ¡®If Jackson hits a home run before me, I¡¯m going to be pretty upset,¡¯¡± Cowser said.

Holliday (MLB Pipeline¡¯s No. 1 overall prospect) played his first two big league games this week at Fenway Park, but it was Cowser who stole the show. The 24-year-old outfielder slugged the first two home runs of his MLB career in the Orioles¡¯ 9-4, 10-inning win over the Red Sox on Thursday night, capping a huge series for the 2021 first-round Draft pick.

Cowser continued a torrid start to his 2024 rookie season with a historic breakout in Boston. He became the first player in franchise history to record 10 RBIs in a three-game series at Fenway -- he drove in four on Tuesday, two on Wednesday and four more on Thursday -- while going 6-for-13 with five extra-base hits in the O¡¯s sweep.

As American League East rivals, the Orioles and Red Sox play multiple series every year in Boston. Yet, Cowser¡¯s feat stands alone.

¡°He¡¯s just scratching the surface,¡± said shortstop Gunnar Henderson, who hit the go-ahead two-run homer in the six-run 10th inning.

It was a momentous day for Cowser, even before Thursday¡¯s game began.

Prior to the contest, Cowser and Holliday went inside the fabled Green Monster in left field and left their mark on its historic 112-year-old walls. Per tradition, both placed their signatures there -- with Cowser making sure to find a rare high spot that had been previously untouched.

¡°It¡¯s a really cool ballpark,¡± Cowser said. ¡°It¡¯s one of those ones as a kid you grow up you¡¯re like, ¡®Oh, I just want to visit it,¡¯ let alone play in it. It¡¯s a blessing.¡±

Now, Cowser can say he¡¯s hit a home run on top of the Monster, too.

In the fifth, Cowser swatted an opposite-field solo shot off Red Sox starter Garrett Whitlock that clanged off the high left-field seats before bouncing back onto the field. The milestone homer came in his 37th big league game and his 82nd at-bat.

¡°I was trying to keep it under 100 at-bats,¡± Cowser said with a smirk.

Cowser¡¯s second MLB home run was a no-doubter. He jumped on a 3-0 pitch from right-hander Isaiah Campbell and jolted it a Statcast-projected 438 feet over Baltimore¡¯s bullpen in right field. It pushed the Orioles¡¯ lead to 9-3, putting the game out of reach.

¡°That was a ¡®Wow¡¯ moment there with the 3-0 when he goes into David Ortiz land,¡± manager Brandon Hyde said. ¡°That was an impressive swing. Awesome to see him go opposite-field homer, too. He did a lot of great things this series.¡±

The O¡¯s were confident that Cowser¡¯s 26-game debut stint last year -- in which he went 7-for-61 (.115) with a .434 OPS -- wasn¡¯t indicative of the type of player he could become. Cowser came into Spring Training motivated to prove that, had a huge spring and then broke camp with the team, making his first career Opening Day roster.

Since then, Cowser hasn¡¯t slowed down. Through 11 games, he is 11-for-24 (.458) with five doubles, two homers, 11 RBIs and a 1.379 OPS.

¡°He¡¯s been a lot of fun to watch,¡± right-hander Grayson Rodriguez said. ¡°I think he¡¯s really starting to come alive, showing everybody the player that he is and the special talent that he is as well.¡±

After making only two starts over Baltimore¡¯s first eight games, Cowser has forced his way into being a regular in the lineup, where he began all three games in Boston.

However, Cowser insists the increase in playing time -- along with the big week stats-wise -- hasn¡¯t necessarily brought a confidence boost.

¡°It doesn¡¯t change much,¡± Cowser said. ¡°This year, I was trying to be a little bit more confident, regardless of what happens. Whether I go 0-for-4 or 4-for-4, I want to forget about it that night and then go into the next day with the same mentality. Really not change my process or change how I go about my business.¡±

So far, that¡¯s going quite well. And Cowser is sure that Holliday (hitless over his first eight at-bats) will join him in the friendly homer competition soon enough.

¡°I know his is coming soon,¡± Cowser said.