Hours before Tuesday’s 6 p.m. ET deadline to finalize their 40-man roster for next month’s Rule 5 Draft, the Red Sox swung a trade with a division rival and designated first baseman Nathaniel Lowe and right-hander Josh Winckowski for assignment.

Right-handed reliever Luis Guerrero is going to the Tampa Bay Rays in exchange for Tristan Gray to Boston.

Guerrero, however, was no longer on the 40-man roster after being designated for assignment, clearing waivers, and being outrighted to the minors earlier this month. Thus, the Red Sox opened a roster spot for Gray by DFA’ing Lowe. Winckowski’s spot will be given to a top prospect they wish to protect from the Rule 5, likely right-hander David Sandlin.

Gray, 29, is coming off his second stint with the Rays, with whom he made his big-league d

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