The Orioles placed Mountcastle on the 10-day injured list Saturday with a right hamstring strain.

Mountcastle had to make an early exit from Friday's contest due to a hamstring issue, and imaging later revealed a strain. While the 28-year-old is out, Coby Mayo will come up from the minors to fill the open spot on the active roster.

Lowe went 2-for-3 with two walks, two runs scored and two RBI in Friday's win over Arizona.

The first baseman produced his second straight multi-hit game while drawing multiple free passes for the first time since May 7. Lowe has endured a tough May overall, slashing .212/.278/.298 through 115 plate appearances even with the recent mini-surge, but he's still come through with 13 RBI and 14 runs in 26 contests, and he appears to be building some momentum heading into June.

Toro started at first base and went 3-for-4 with a double, an RBI and a run scored in Friday's 5-1 win over Atlanta.

First base has been chaotic since Triston Casas (knee) suffered a season-ending injury, but Toro has made a case for himself. He's gone 14-for-42 (.333) with three home runs, four doubles, five RBI and seven runs scored over the last 12 games. However, the Red Sox intend to experiment with Kristian Campbell at first base for at least one game during this weekend's series in Atlanta.

Guerrero went 1-for-3 with three walks, a run scored and an RBI in Friday's win over the A's.

Athletics pitchers issued 11 free passes in total on the night, while every Blue Jays hitter collected at least one hit, leading to an 11-7 victory. Guerrero has reached base safely in an impressive 30 straight games, slashing .288/.407/.468 over that span with six homers, 14 RBI and 23 runs.

Freeman went 3-for-4 with two doubles, one RBI and one run scored in Friday's 8-5 win over the Yankees.

After going hitless in consecutive games for just the second time all year May 23-24 versus the Mets, Freeman has bounced back in a big way with four multi-hit efforts over his last five contests. He is 10-for-20 (.500) with three RBI and three doubles in that span. The star first baseman is batting .368 with a 1.066 OPS while adding nine home runs, 16 doubles, 37 RBI, 31 runs scored and one triple over 46 contests this season.

Olson went 1-for-4 with an RBI in Friday's 5-1 loss to Boston.

Olson tallied his 15th RBI of the month and his 30th of the season, and he remains a strong source of power despite a subpar batting average. Across 103 at-bats in May, the All-Star first baseman is hitting just .243 but has eight home runs, five doubles and 15 RBI. Olson entered Friday with an elite 18.7 percent barrel rate and 56.0 percent hard-hit rate in 2025, and he's begun to return to form in the slugging department following a slow start to the year in that area.

Mountcastle was removed from Friday's game against the White Sox due to right hamstring discomfort, Andy Kostka of TheBaltimoreBanner.com reports.

Mountcastle went 2-for-3 with a steal and a run scored prior to being replaced in the eighth inning, with Cooper Hummel entering in right field while Ryan O'Hearn shifted over to first base. Mountcastle will undergo further tests and the Orioles should provide an update on his injury during or shortly after Friday's contest.

Walker (hand) is starting at first base and hitting cleanup Friday against the Rays.

He exited Wednesday's game after getting hit on the hand by a pitch, but X-rays were negative and he just needed one day off before getting back in the mix. Walker is hitting .229 with three home runs in 25 games this month.

Harper (elbow) is not in Friday's lineup against the Brewers, Scott Lauber of The Philadelphia Inquirer reports.

Harper will miss a third straight game with a right elbow bruise. Alec Bohm is starting at first base while Edmundo Sosa mans third. Harper called himself "super day-to-day" Friday, but he hasn't tried swinging a bat yet and likely won't Friday, per Paul Casella of MLB.com, so it's possible this turns into an IL stint. When Betts returns, he'll be wearing a new elbow brace, according to Matt Gelb of The Athletic.

The Marlins designated Mervis for assignment Friday.

Mervis' .175/.254/.383 slash line through 134 plate appearances this season was enough for the Marlins to move on after acquiring him from the Cubs during the offseason. The 27-year-old has yet to find much success across parts of three-big league seasons with a .560 OPS, but he could still receive some interest on waivers given his prospect pedigree.