BOSTON -- After another mid-game malfunction in the bullpen in Sunday¡¯s 12-4 loss to the Rays, the Red Sox designated struggling relievers Hirokazu Sawamura and Austin Davis for assignment.

As the Red Sox prepared to open a three-game series in Minneapolis on Monday night, righty relievers Zack Kelly and Kaleb Ort were added from Triple-A Worcester to fill the open spots on the roster.

The Red Sox have struggled all season in the bullpen, as evidenced by a 4.54 ERA, which ranks 27th in the Majors.

Sawamura, a 34-year-old righty, gave up four hits, three runs and two walks in one inning on Sunday, throwing 37 pitches. The Sox signed Sawamura, out of Japan, to a two-year contract in February of 2021. In 104 career games, Sawamura has a 3.39 ERA, walking 59 and striking out 101 in 103 2/3 innings.

Davis, a 29-year-old lefty, gave up three hits and four runs (two earned) in two innings. He threw 37 pitches in a particularly frustrating eighth inning. The Red Sox acquired Davis at the July 31 Trade Deadline in ¡¯21. In 134 games in his career, Davis has a 5.49 ERA.

The 27-year-old Kelly has never pitched in MLB. In 44 games for Worcester this season, he has a 2.72 ERA.

Ort, 30, pitched in 12 games for the Red Sox earlier in the season, giving up 24 hits and 15 earned runs in 15 innings. He has been solid for Worcester, notching a 2.88 ERA in 39 games.