Marcelo Mayer's Double-A ride hit a new bump on Saturday, as the top Red Sox prospect was assigned to the 7-day injured list retroactive to Aug. 3. Mayer is suffering from left shoulder inflammation, a source told MLB.com's Ian Browne.

The 20-year-old shortstop, MLB's No. 3 prospect, began the year with High-A Greenville and earned an end-of-May promotion to Portland with a .290/.366/.524 slash line and seven home runs through 35 games. Mayer's power has continued to show out at the higher level (six homers, eight doubles and a triple), but he batted .176 through his first month with the Sea Dogs.

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He put together 10 hits over two series in the second half of July, but he was on a 1-for-21 skid over the five most recent games he played, giving him a .189/.254/.355 line over 43 Double-A games.

Mayer features a 60-grade hit tool and 55-grade power, and his defensive skills profile as above average. A prep star out of Chula Vista, Calif., he was Boston's first pick -- No. 4 overall -- in the 2021 Draft. Over his 195-game Minor League career, he has 29 homers, 33 steals and a .261/.359/.460 slash line.